Forming method of contact hole, and manufacturing method of semiconductor device, liquid crystal display device and EL display device

ABSTRACT

When forming a contact hole by a conventional manufacturing step of a semiconductor device, a resist is required to be formed on almost entire surface of a substrate so as to be applied on a film other than an area in which a contact hole is to be formed, leading to drastically reduced throughput. According to a forming method of a contact hole and a manufacturing method of a semiconductor device, an EL display device and a liquid crystal display device of the invention, an island shape organic film is selectively formed over a semiconductor layer, a conductive layer or an insulating layer, and an insulating film is formed around the island shape organic film to form a contact hole. Therefore, a conventional patterning using a resist is not required, and high throughput and low cost can be achieved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacturing method of asemiconductor device, a liquid crystal display device and an EL displaydevice using a droplet discharge method typified by ink jet printing. Inparticular, the invention relates to a forming method of a contact holeprovided in the semiconductor device.

2. Description of the Related Art

In the manufacture of semiconductor devices, liquid crystal displaydevices or EL display devices, it has been suggested that a dropletdischarge apparatus is used to form thin films and wiring patterns inorder to reduce the equipment cost and simplify the steps.

In such a case, a contact hole of a semiconductor device is formed bythe steps of prebaking a resist applied on an entire surface of asubstrate, forming a resist pattern by photolithography in which UV raysand the like are irradiated through a mask and developed, and etchingand removing an insulating film, a semiconductor film, a metal film andthe like that are to be a contact hole using the resist pattern as amask.

Patterning can be performed relatively easily by an exposure apparatusin the case of a glass substrate or a display panel being small. Whenthe size of a substrate increases, however, an entire surface of adisplay panel cannot be processed at a time by one exposure step.Accordingly, an area on which a photo resist is applied is divided intoa plurality of blocks and an exposure step is sequentially performed foreach predetermined block, thereby an entire surface of a substrate isexposed (for example, see Patent Document 1).

[Patent Document 1] Japanese Patent Laid-Open No. 11-326951

However, in the case of forming a contact hole by a conventionalmanufacturing step of a semiconductor device, a resist is required to beformed on almost entire surface of a substrate so as to be applied on afilm other than an area in which a contact hole is formed, leading todrastically reduced throughput. Even when throughput is improved, in thecase where the amount of the resist being applied and the surfacequality of a base film are not sufficiently controlled, the contact holeis also covered with the resist and contact defects may occur.

SUMMARY OF THE INVENTION

In view of the foregoing problems, the invention provides a formingmethod of an excellent contact hole as well as an interlayer film, aplanarizing film and an insulating film such as a gate insulating filmthat are provided in the periphery thereof by a simplified step.Further, the invention provides a manufacturing method of asemiconductor device, which is low in cost and high in throughput andyield.

(1) According to the invention, a forming method of a contact holecomprises the steps of forming an organic film over a semiconductorlayer, a conductive layer or an insulating layer, forming a mask patternin an area over the organic film, in which a contact hole is to beformed, removing the mask pattern after patterning the organic film toisland shape using the mask pattern as a mask, and then removing theisland shape organic film after forming an insulating film around theisland shape organic film.

The organic film is a film that contains an organic material as a maincomponent and has liquid repellency (water repellency) to an insulatingfilm formed later. Therefore, when the organic film is formedselectively, for example to island shape, on an area in which a contacthole is to be formed, an insulating film is formed only in the peripheryof the island shape organic film by applying the insulating film sincethe island shape organic film repels an insulating material of theinsulating film. As a result, a contact hole is formed in a self alignedmanner in an area in which the insulating film is not formed (over anarea in which the island shape organic film is formed) (see FIGS. 1A to1F).

The insulating film, for example, an interlayer insulating film or aplanarizing film of a TFT (thin film transistor), is formed of anorganic material such as a polyimide-based resin, an acryl-based resin,a polyamide-based resin, and a siloxane-based resin (a material having abackbone structure obtained by binding silicon to oxygen and having atleast one hydrogen substituent, or further having at least onesubstituent selected from fluorine, an alkyl group, or aromatichydrocarbon in addition to hydrogen). A material having liquidrepellency to such an organic material is used for an organic film,which is typified by a silane coupling agent. The silane coupling agentis a silicon compound represented by R_(n)—Si—X_(4-n) (n=1, 2, 3). Here,R is a substance that contains a relatively inert group such as an alkylgroup or a reactive group such as a vinyl group, an amino group and anepoxy group. Further, X is formed with halogen, a methoxy group, anethoxy group, a hydroxyl group of the substrate surface such as anacetoxy group, or a hydrolysate group that is bondable with absorbedwater by condensation. A fluorinated silane coupling agent is typifiedby fluoroalkyl silane (FAS).

The organic film may be formed by plasma treatment under an atmospherecontaining fluorine such as CF₄ and CHF₃. According to this, an organicfilm containing fluorine can be obtained. The thickness of the organicfilm can be controlled by treatment conditions and time. The organicfilm formed by plasma treatment can be removed by plasma treatment(ashing) under O₂ atmosphere.

Note that the combination of the organic film and the insulating film isnot limited to the foregoing, and it can be arbitrarily determined aslong as the organic film has liquid repellency to the insulating film.In addition, the insulating film is not limited to an interlayerinsulating film and a planarizing film, and It includes any otherinsulating films such as a gate insulating film of a semiconductordevice such as a TFT, and an insulating film (also called a bank) of anEL display device formed around a light emitting layer, an electroninjection layer, an electron transporting layer, a hole injection layer,and a hole transporting layer each containing an organic or inorganiccompound (hereinafter, collectively called a light emitting layer andthe like).

In order to pattern an organic film, the organic film is applied on anentire surface by spin coating, slit coating, dip coating, spraycoating, a droplet discharge method (ink jet printing, screen printing,offset printing or the like), doctor knife, roll coater, curtain coater,knife coater, or the like. Then, a mask pattern is formed in an area inwhich a contact hole is to be formed, and the organic film is removedusing the mask pattern as a mask. Accordingly, an organic film can beformed selectively, for example to island shape. The organic film may beremoved by various methods such as O₂ ashing and atmospheric pressureplasma depending on a material of the organic film. It is needless tosay that the organic film may be removed by plasma etching, wet etching,ashing or the like.

Note that in this specification, the organic film includes both of anorganic film formed by the aforementioned coating methods and an organicfilm formed by the plasma treatment.

The aforementioned etching includes wet etching using chemicals and dryetching or plasma etching using an active radical or reactive gasplasma. In this specification, the etching means any etching methodincluding them. The chemicals used in wet etching are typified byhydrofluoric acid (HF), nitric acid, acetic acid, thermal phosphoricacid, a mixture of them, or a mixture obtained by diluting them withwater or ammonium fluoride, though the invention is not limited tothese. The gas used in dry etching is typified by chlorine-based gassuch as Cl₂, BCl₃, SiCl₄, and CCl₄, fluorine-based gas such as CF₄, SF₆,NF₃, and CHF₃, O₂, a mixed gas of them, or a gas obtained by mixing themwith a noble gas such as He and Ar, though the invention is not limitedto these.

The mask pattern may be formed of a water soluble resin such as PVA(polyvinyl alcohol), a photosensitive or non-photosensitive organicmaterial such as polyimide, acryl, polyamide, resist, andbenzocyclobutene, or an organic resin such as siloxane. It is preferableto selectively form these materials by a droplet discharge method in anarea in which a, contact hole is to be formed, though they may bepatterned through conventional exposure and development steps. After theorganic film is patterned using the mask pattern, these materials areremoved.

In particular when PVA is used, the mask pattern can be easily removedby H₂O. When polyimide or acryl is used, the mask pattern can be easilyremoved by a stripper such as “Nagase resist strip N-300” (product ofNagase ChemteX Co., Ltd., hereinafter referred to as an N300 stripper)that contains as main components 2-amino ethanol and glycol ether, and“Stripper 710” (product of Tokyo Ohka Kogyo Co., Ltd., hereinafterreferred to as a 710 stripper) that contains as main componentso-dichlorobenzene, phenol, and alkyl benzene sulfonate. Needless to say,the mask pattern may be removed by ashing or etching These removingmethods can also be adopted in the case where the mask pattern ispatterned as is in conventional technologies.

Note that the mask pattern is not necessarily removed, and it may remainwhen a material of the mask pattern has liquid repellency to aninsulating film formed later. In such a case, the mask pattern and theorganic film may be removed simultaneously or sequentially after theformation of a contact hole.

Note also that the organic film pattern may be formed directly andselectively by a droplet discharge method or the like.

The contact hole is typified by, for example in a semiconductor devicesuch as a TFT, a contact hole for connecting impurity regions such as asource region and a drain region to a source wiring and a drain wiring(also called a 2nd wiring) respectively. However, it is needless to saythat the contact hole is not limited to this, and the invention can beapplied to the formation of any other contact holes required in asemiconductor device such as a TFT (including a transistor used for anintegrated circuit (IC) such as an LSI, a memory and a logic circuit aswell as a semiconductor device such as a TFT used for an LCD and an ELdisplay device), and a liquid crystal display device, an EL displaydevice and the like that are driven by TFTs. For example, since a lightemitting layer or the like formed of an organic or inorganic compound isformed between the aforementioned banks in an EL display device (seeFIG. 11E), an organic film is selectively formed in an area in which thelight emitting layer or the like is to be formed, and then an insulatingmaterial used for the banks is applied on an entire surface, thereby thebanks can be formed in predetermined areas.

(2) According to the invention, a manufacturing method of asemiconductor device comprises the steps of forming a gate electrodeover a substrate, forming a semiconductor layer over the gate electrodewith a gate insulating film interposed therebetween, forming an organicfilm over the semiconductor layer, forming a mask pattern in an areaover the organic film, in which a contact hole is to be formed, removingthe mask pattern after patterning the organic film to island shape usingthe mask pattern as a mask, forming a contact hole by removing theisland shape organic film after forming an insulating film around theisland shape organic film, and forming a conductor in the contact hole.

The semiconductor device here mainly means a field effect transistor(FET) (also called a unipolar transistor). The FET is classified by thestructure of a gate electrode portion into an insulated gate FET(IGFET); a metal insulator semiconductor FET (MISFET) using a metal gateelectrode; a metal oxide semiconductor FET (MOSFET) using a siliconoxide film as an insulating film; a thin film transistor (TFT) in whicha semiconductor thin film such as amorphous silicon (a-Si) andpolycrystalline silicon (p-Si) is formed over an insulator such as glassand ceramic and a MOSFET is formed within the semiconductor thin film,and the like. These transistors are each classified into an N-channeltransistor and a P-channel transistor. A circuit configured by theN-channel transistor and the P-channel transistor (e.g., an invertercircuit) is called a CMOS (Complementary MOS) circuit.

The semiconductor device includes a liquid crystal panel, an EL paneland the like each having the aforementioned transistors using asemiconductor material.

The structure of a transistor is classified into a coplanar structure inwhich source, drain and channel regions are formed of a singlesemiconductor layer; and a staggered structure in which source, drainand channel regions are formed of different semiconductor layers. Thecoplanar structure and the staggered structure are each classified intoa top gate structure and a bottom gate structure. Therefore, when asemiconductor layer is formed over a gate electrode with a gateinsulating film interposed therebetween in a top gate transistor, thesemiconductor layer, the gate insulating film and the gate electrode arestacked in this order. Meanwhile, in a bottom gate transistor, the gateelectrode, the gate insulating film and the semiconductor layer arestacked in this order.

The conductor is formed in the contact hole in order to be connected tothe semiconductor layer. The semiconductor layer and the conductor maybe connected directly or indirectly with another conductive film orsemiconductor film interposed therebetween.

Other structures and interpretation of words and phrases are similar tothose in the aforementioned description (1).

(3) According to the invention, a manufacturing method of an EL displaydevice comprises the steps of forming a gate electrode over a substrate,forming a semiconductor layer over the gate electrode with a gateinsulating film interposed therebetween, forming an organic film overthe semiconductor layer, forming a mask pattern in an area over theorganic film, in which a contact hole is to be formed, removing the maskpattern after patterning the organic film to island shape using the maskpattern as a mask, forming a contact hole by removing the island shapeorganic film after forming an insulating film around the island shapeorganic film, forming a conductor in the contact hole, and forming alayer containing organic or inorganic compounds over the conductor.

The EL display device is a display device having a light emittingelement utilizing electro luminescence (EL), and is broadly classifiedinto a passive matrix type and an active matrix type. In particular, anEL display device controlled by a semiconductor device such as a TFT iscalled an active matrix EL display device (EL display).

In the light emitting clement, a light emitting layer which is a stackof layers of a film containing an organic or inorganic compound havingdifferent carrier transporting characteristics is sandwiched between apair of electrodes, and the light emitting layer is formed so that holescan be injected from an electrode and electrons can be injected from theother electrode. The light emitting element uses a phenomenon in whichholes injected from an electrode and electrons injected from the otherelectrode are recombined to excite luminescent centers and light isproduced when the excited state returns to a ground state. The injectioncharacteristics of the holes and the electrons into the light emittinglayer depend on the work function or the like (minimum energy requiredto extract an electron from the surface of metal or semiconductor to asurface immediately outside thereof) of a material forming an electrode.It is preferable that the electrode to which holes are injected has highwork function, and the electrode to which electrons are injected has lowwork function.

When an organic compound material is used at least for a light emittinglayer, the EL display device is called an organic EL display. When aninorganic compound material is used at least for a light emitting layer,the EL display device is called an inorganic EL display. In the case ofan organic compound material and an inorganic compound material bothbeing used, the EL display device is called a hybrid EL display or thelike.

The conductor is formed in the contact hole in order to electricallyconnect the semiconductor layer to the light emitting layer and thelike. In an active matrix EL display device, a semiconductor device suchas a TFT functions as a switch for determining whether a current issupplied to an EL element or not, and a path of current flowing to theEL element. Thus, a current in the semiconductor layer flows to the ELelement through the conductor. Note that the conductor may also functionas a pixel electrode that is directly connected to the EL element.Alternatively, a pixel electrode may be provided separately. Further,the semiconductor layer and the conductor may be connected directly orindirectly with another conductive film or semiconductor film interposedtherebetween.

Other structures and interpretation of words and phrases are similar tothose in the aforementioned descriptions (1) and (2).

(4) According to the invention, a manufacturing method of a liquidcrystal display device comprises the steps of forming a gate electrodeover a substrate, forming a semiconductor layer over the gate electrodewith a gate insulating film interposed therebetween, forming an organicfilm over the semiconductor layer, forming a mask pattern in an areaover the organic film, in which a contact hole is to be formed, removingthe mask pattern after patterning the organic film to island shape usingthe mask pattern as a mask, forming a contact hole by removing theisland shape organic film after forming an insulating film around theisland shape organic film, forming a conductor in the contact hole, andforming a liquid crystal layer over the conductor.

The liquid crystal display device is a display device having liquidcrystal molecules that have an intermediate state between liquid andsolid and are arranged in a loosely ordered fashion in their naturalstates. The display device utilizes the properties of liquid crystalmolecules of which the arrangement changes when a voltage is applied,and the display device is broadly classified into a passive matrix typeand an active matrix type. In particular, a liquid crystal displaydevice controlled by a semiconductor device such as a TFT is called anactive matrix liquid crystal display device (AM-LCD). An LCD is alsoclassified into two types: a transmissive type using a back light as alight source; and a reflective type using as a light source outsidelight such as sunlight and interior light.

A liquid crystal layer including liquid crystal molecules can be formedby dip coating, a droplet discharge method or the like. As a liquidcrystal material, any type of liquid crystal molecule can be employedsuch as a positive nematic liquid crystal, a negative nematic liquidcrystal, a twisted nematic (TN) liquid crystal, a super twisted nematic(STN) crystal, a ferroelectric liquid crystal, and an antiferroelectricliquid crystal.

The conductor is formed in the contact hole in order to electricallyconnect the semiconductor layer to a pixel electrode that applies avoltage to the liquid crystal layer. In an active matrix liquid crystaldisplay device, a semiconductor device such as a TFT functions as aswitch for selecting whether to apply a voltage to a liquid crystallayer or not. Note that the conductor may also function as a pixelelectrode, or a pixel electrode may be provided separately. Further, thesemiconductor layer and the conductor may be connected directly orindirectly with another conductive film or semiconductor film interposedtherebetween.

Other structures and interpretation of words and phrases are similar tothose in the aforementioned descriptions (1) and (2).

According to the invention, an organic film having liquid repellency toan insulating material used for an interlayer insulating film, aplanarizing film, a gate insulating film and the like is selectivelyformed in an area over a semiconductor layer, a conductive layer or aninsulating layer, in which a contact hole is to be formed. Then,insulating films are formed around the organic film, thereby theseinsulating films can be formed in a desired area and a contact hole canbe formed between the insulating films in a self-aligned manner. Inaddition, the contact hole and the insulating films can be formedwithout exposure and development steps that require a resist masks Thus,forming steps can be considerably simplified as compared withconventional steps.

Further, when a gate electrode, a mask pattern, a conductor and the likeare formed by a droplet discharge method, a droplet containing amaterial of these films can be discharged in an arbitrary area bychanging the relative position between a substrate and a nozzle fordischarging a droplet. The thickness and the width of a pattern to beformed can be adjusted by the nozzle diameter, the discharge amount ofdroplet, and relative relationship between the movement speeds of thenozzle and the substrate to be applied with the droplet. Thus, thematerial of the films can be accurately discharged to form the films ina predetermined area. In addition, since a patterning step, that isexposure and development steps using a resist mask can be omitted,significant simplification of the forming steps and the cost reductioncan be attempted. Further, by using the droplet discharge method,patterns can be formed in an arbitrary area and the thickness and thewidth of the patterns to be formed can be adjusted. Therefore, evena-large semiconductor clement substrate with a side of 1 to 2 m can bemanufactured with high yield and at low cost.

As set forth above, a contact hole and an insulating film around thecontact hole in a semiconductor device can be accurately formed bysimple steps. Further, it is possible to provide a manufacturing methodof a semiconductor device, which is low in cost and high in throughputand yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1F are views showing forming steps of a contact holeaccording to the invention.

FIGS. 2A to 2E are views showing manufacturing steps of a semiconductordevice according to the invention (a channel protected TFT).

FIGS. 3A to 3D are views showing manufacturing steps of a semiconductordevice according to the invention (a channel protected TFT).

FIGS. 4A to 4D are views showing manufacturing steps of a semiconductordevice according to the invention (a channel etched TFT).

FIGS. 5A to 5C are views showing manufacturing steps of a semiconductordevice according to the invention (a channel etched TFT).

FIGS. 6A to 6D are views showing manufacturing steps of a semiconductordevice according to the invention (a top gate TFT).

FIGS. 7A to 7D are views showing manufacturing steps of a semiconductordevice according to the invention (a top gate TFT).

FIGS. 8A to 8C are views showing base film pretreatment steps.

FIG. 9A is a top plan view of a pixel of an EL display device accordingto the invention and FIG. 9B is a circuit diagram thereof (forwardstaggered).

FIG. 10A is a top plan view of a pixel of an EL display device accordingto the invention and FIG. 10B is a circuit diagram thereof (invertedstaggered).

FIGS. 11A to 11E are views showing manufacturing steps of an EL displaydevice according to the invention.

FIGS. 12A to 12C are views respectively showing top emission, bottomemission and dual emission light emitting devices.

FIG. 13 is a block diagram showing the main configuration of an EL TVset using the invention.

FIG. 14 is a top plan view of a pixel of a liquid crystal display deviceaccording to the invention.

FIGS. 15A to 15C are views showing manufacturing steps of a liquidcrystal display device according to the invention.

FIG. 16 is a view showing a droplet discharge system.

FIG. 17 is a block diagram showing a main configuration of a liquidcrystal TV set using the invention.

FIGS. 18A and 18B are views showing a modularized EL display panel orLCD panel.

FIG. 19 is a view showing a modularized display panel using theinvention.

FIG. 20 is a circuit diagram showing the case in which a scan linedriver circuit of a display panel using the invention is structured byTFTs (a pulse output circuit).

FIG. 21 is a circuit diagram showing the case in which a scan linedriver circuit of a display panel using the invention is structured byTFTs (a buffer circuit).

FIG. 22 is a view showing a surface structure of glass modified by asilane coupling agent.

FIGS. 23A and 23B are views showing a structure of conductive particles.

FIG. 24 is a view showing a droplet discharge system.

FIGS. 25A to 25C are views showing examples of an electronic apparatususing the invention.

FIG. 26 is a view showing the size of a mask pattern which depends onthe concentration of solute.

DETAILED DESCRIPTION OF THE INVENTION

Although the invention will be described by way of embodiment modes andembodiments with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless such changes andmodifications depart from the scope of the invention, they should beconstructed as being included therein. For example, the invention can beimplemented by arbitrarily combining each of the embodiment modes andthe embodiments. Therefore, the invention is not limited to thedescriptions in the embodiment modes and the embodiments.

Although the invention provides a manufacturing method of all kinds ofsemiconductor devices, liquid crystal display devices and EL displaydevices using a maskless process such as a droplet discharge method, notall the steps are required to be performed by a maskless process, but itis only required that at least a part of the steps includes a masklessprocess. Accordingly, even when droplet discharge steps are only used inthe manufacturing method described below, other conventionalmanufacturing steps such as a patterning step may be adopted instead.

Embodiment Mode 1

In this embodiment mode, a forming method of a contact hole according tothe invention is described with reference to FIGS. 1A to 1F.

First, a conductive or semiconductor film 11 is formed over a substrate10, and then an organic film 12 is applied on an entire surface of thesubstrate 10 by spin coating, slit coating or the like (FIG. 1A). Theorganic film 12 is typically formed of a fluorine-based silane couplingagent such as fluoroalkyl silane, though the invention is not limited tothis.

Next, a mask pattern 13 is selectively formed in an area in which acontact hole is to be formed (FIG. 1B). It is desirable to form the maskpattern 13 selectively by a droplet discharge method. The mask pattern13 is formed of a water soluble resin such as PVA (polyvinyl alcohol) oran organic resin such as polyimide, acryl and siloxane, though theinvention is not limited to this.

Then, the organic film 12 is removed using the mask pattern 13 as amask, thereby an island shape organic film 14 is obtained (FIG. 1C). Theorganic film 12 is desirably removed by O₂ ashing or atmosphericpressure discharge plasma, though the invention is not limited to this.Instead, UV ozone treatment, laser treatment or the like can be adopted.

Subsequently, the mask pattern 13 is removed (FIG. 1D). In the case ofPVA being used for the mask pattern 13, for example, the mask pattern 13can be easily removed by H₂O (water washing). When polyimide or acryl isused for the mask pattern 13, it can be easily removed by the N300stripper or the 710 stripper. It is needless to say that the maskpattern 13 may be removed by ashing or etching.

Although the mask pattern 13 is removed in this embodiment mode, it mayremain in the case of having liquid repellency to an insulating filmformed later. Even when the mask pattern 13 does not have liquidrepellency, it can be treated with CF₄ plasma to obtain liquidrepellency after forming the mask pattern 13.

Then, an insulating film 15 is applied over an entire surface of thesubstrate 10. In this embodiment mode, the insulating film 15 is formedof siloxane that is a heat resistant resin, though the invention is notlimited to this. The insulating film 15 is not formed over the islandshape organic film 14 since the island shape organic film 14 repels theinsulating film 15. Thus, a contact hole 16 is formed in a self-alignedmanner. At this time, the insulating film 15 is tapered, thereby thestep coverage with a conductive film formed later can be improved. (FIG.1E) The island shape organic film 14 is removed thereafter by O₂ ashing,atmospheric plasma or the like. Instead, UV ozone treatment, lasertreatment or the like may be adopted.

Next, a composition containing a conductive material is discharged inthe contact hole 16 by a droplet discharge method, thereby a conductor17 is formed to be connected to the conductive or semiconductor film 11on the bottom layer. (FIG. 1F) In the case where an insulating film isformed over the conductive or semiconductor film 11, it is removed byetching or the like to form the contact hole 16. This etching isdesirably performed by using an etchant having high etch selectivity(ratio between the etching rate a of a material to be etched and theetching rate b of an etching mask material and a base film material:a/b) relative to the conductive or semiconductor film 11 on the bottomlayer.

The aforementioned forming method of a contact hole can be applied tothe formation of any other contact holes required in a semiconductordevice such as a TFT (including a transistor used for an integratedcircuit (IC) such as an LSI, a memory and a logic circuit as well as asemiconductor device such as a TFT used for an LCD and an EL displaydevice), and a liquid crystal display device, an EL display device andthe like that are driven by TFTs.

Embodiment Mode 2

In this embodiment mode, a manufacturing method of a bottom gate TFTaccording to the invention, in particular a manufacturing method of achannel protected TFT is described with reference to FIGS. 2A to 2E andFIGS. 3F to 3I.

First, base film pretreatment is applied to an area over a substrate, inwhich at least a gate electrode is to be formed. In this embodimentmode, a titanium oxide (TiO_(x)) film 103 is formed over an entiresurface of a substrate 100 (FIG. 2A). This pretreatment allows toincrease the adhesiveness between the substrate 100 and a conductivefilm (a gate electrode 102 herein) that is to be formed later bydischarging a composition containing a conductive material. When atitanium oxide film is formed, light transmissivity can be increased.Instead of titanium oxide, polyimide, acryl or a heat resistant resinsuch as siloxane may be used as well. Alternatively, plasma treatmentmay be performed.

It is also possible to use a photocatalytic substance such as strontiumtitanate (SrTiO₃), cadmium selenide (CdSe), potassium tantalate (KTaO₃),cadmium sulfide (CdS), zirconium oxide (ZrO₂), niobium oxide (Nb₂O₅),zinc oxide (ZnO), iron oxide (Fe₂O₃), and tungsten oxide (WO₃) as wellas titanium oxide. Instead, a layer containing 3d transition elements oran oxide, nitride, or oxynitride thereof may be formed. The 3dtransition elements include Ti (titanium), Sc (scandium), V (vanadium),Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu(copper), and Zn (zinc). The aforementioned base film pretreatment isdesirably performed in order to increase the adhesiveness between thesubstrate and the conductive film.

Base film pretreatment using a conductive film such as a titanium filmcan be performed by some methods as shown in FIGS. 8A to 8C. FIG. 8Ashows a method similar to that shown in FIG. 2A, in which a conductiveoxide film (a TiO_(x) film 830 herein) is formed over an entire surfaceof the substrate or at least under a gate electrode 802. FIG. 8B shows amethod in which the gate electrode 802 is formed after a conductive filmsuch as a titanium film (a Ti film 829 herein) is formed over an entiresurface of the substrate, and the Ti film 829 is oxidized (baking, or O₂ion injection and then baking) using the gate electrode 802 as a mask,thereby a TiO_(x) film 831 is formed around the gate electrode 802.According to such a method, gate electrodes can be prevented from beingshort-circuited. FIG. 8C shows a method in which the gate electrode 802is formed after the Ti film 829 is formed over an entire surface of thesubstrate, and the exposed Ti film 829 is etched using the gateelectrode 802 as a mask. In that case, gate electrodes can be preventedfrom being short-circuited.

Next, a composition containing a conductive material (hereinafterreferred to as conductive paste) is discharged from a nozzle 101 overthe titanium oxide film 103, thereby the gate electrode 102 is formed(FIG. 2A). The gate electrode 102 is formed by drying the dischargedcomposition at a temperature of 100° C. for three minutes, then bakingit at a temperature of 200 to 350° C. for 15 to 30 minutes under anitrogen or oxygen atmosphere, though the conditions are not limited tothese. Note that the form of the nozzle 101 is not limited to the oneshown in FIG. 2A.

If the baking is performed in a mixed atmosphere of O₂ and N₂, anorganic material such as a binder (a thermosetting resin) contained inthe conductive paste (e.g., Ag paste) is decomposed, and a conductivefilm containing hardly any organic material can be obtained. Inaddition, a surface of the film can be planarized. The mixing ratio ofO₂ relative to N₂ is preferably 10 to 30% (more preferably, about 25%).A solvent in the conductive paste is volatilized by discharging theconductive paste under low pressure. Consequently, heat treatmentthereafter can be omitted, or the time for the heat treatment can bereduced.

Various materials can be selected as the conductive material dependingon the function of the conductive film. Typically used for theconductive material is silver (Ag), copper (Cu), gold (Au), nickel (Ni),platinum (Pt), chromium (Cr), tin (Sn), palladium (Pd), iridium (Ir),rhodium (Rh), ruthenium (Ru), rhenium (Re), tungsten (W), aluminum (Al),tantalum (Ta), indium (In), tellurium (Te), molybdenum (Mo), cadmium(Cd), zinc (Zn), iron (Fe), titanium (Ti), silicon (Si), germanium (Ge),zirconium (Zr), barium (Ba), antimony lead, tin oxide antimony, fluoridedoped zinc oxide, carbon, graphite, glassy carbon, lithium, beryllium,sodium, magnesium, potassium, calcium, scandium, manganese, gallium,niobium, sodium-potassium alloys, magnesium-copper mixtures,magnesium-silver mixtures, magnesium-aluminum mixtures, magnesium-indiummixtures, aluminum-aluminum oxide mixtures, lithium-aluminum mixtures,or the like, or silver halide particles, dispersed nanoparticles, indiumtin oxide (ITO) used as a transparent conductive film, zinc oxide (ZnO),zinc oxide added with gallium (GZO), indium zinc oxide (IZO) in which 2to 20% of zinc oxide is mixed into indium oxide, organic indium,organotin, titanium nitride, or the like. In addition, silicon (Si) orsilicon oxide (SiO_(x)) may be contained in the paste or the target forsputtering especially as a material used for a transparent conductivefilm. For example, a conductive material in which silicon oxide iscontained in ITO (generally referred to as ITO—SiO_(x); however,hereinafter referred to as ITSO or NITO for convenience) may be used.Further, layers of these materials may be stacked to form a desiredconductive film.

The diameter of a nozzle used as a droplet discharge means is set at 0.1to 50 μm (preferably, 0.6 to 26 μm), and the amount of the compositiondischarged from the nozzle is set at 0.00001 to 50 pl (preferably,0.0001 to 10 pl). The discharge amount increases in proportion to thediameter of the nozzle. Further, the distance between an object and anorifice of the nozzle is preferably as short as possible, and reduced toabout 0.1 to 2 mm in order to discharge the composition on a desiredarea.

The composition discharged from an orifice is preferably a solution inwhich gold, silver or copper is dissolved or dispersed in a solvent inview of the resistivity. More preferably, silver or copper that has lowresistance may be used. Note that, in the case of copper being used, itis preferable to provide a barrier film for preventing impurities fromentering. Used as the solvent may be esters such as butyl acetate andethyl acetate, alcohols such as isopropyl alcohol and ethyl alcohol, oran organic solvent such as methyl ethyl ketone and acetone. In the caseof copper being used for a wiring, a barrier film may be formed of aninsulating or conductive material containing nitrogen such as siliconnitride, silicon oxynitride, aluminum nitride, titanium nitride, andtantalum nitride (TaN), and such a material may be applied by a dropletdischarge method.

The viscosity of a composition used in the droplet discharge method ispreferably 300 mPa·s or less for preventing drying and allowing thecomposition to be discharged smoothly from the orifice. The viscosity ofthe composition, the surface tension, or the like may be setappropriately in accordance with the solvent or the application. Forexample, the viscosity of a composition in which ITO, ITSO, organicindium, or organotin is dissolved or dispersed in a solvent is 5 to 50mPa·s; the viscosity of a composition in which silver is dissolved ordispersed in a solvent is 5 to 20 mPa·s; and the viscosity of acomposition in which gold is dissolved or dispersed in a solvent is 10to 20 mPa·s.

It is preferable that the diameter of the conductor particles is assmall as possible in order to prevent each nozzle from clogging or tomake fine patterns, and more preferably, each particle has a diameter of0.1 μm or less, though it depends on the diameter of each nozzle or thedesired pattern shape. Each composition may be formed by a known methodsuch as an electrolytic method, an atomization method and wet reduction,and the particle size is generally about 0.5 to 10 μm. Note that, in thecase of the composition being formed by gas evaporation, nanoparticlesprotected with a dispersant are as fine as about 7 nm, and thenanoparticles are dispersed stably at a room temperature and behavesimilarly to liquid without aggregation in a solvent when they are eachprotected with a coating. Therefore, it is preferable to use a coating.

Conductive paste using conductive nanoparticles is called nanopaste. Forexample, conductive particles of Ag or Au preferably have a diameter of3 to 7 nm.

The metal content of the nanopaste is preferably in the range of 10 to75 wt %. For example, silver nanopaste has a metal content of 40 to 60wt %, and gold nanopaste has a metal content of 30 to 50 wt %. Thesolvent content is preferably in the range of 20 to 80%; and theadditive content in the range of 10 to 20%. As the solvent, tetradecaneis typically used for the silver nanopaste and AF solvent (low aromaticsolvent containing naphthene/paraffin=about 8/2) is typically used forthe gold nanopaste. The viscosity of the silver nanopaste and the-goldnanopaste may preferably be 5 to 20 mPa·s and 10 to 20 mPa·s,respectively.

When impurities such as Cl, Fe, K, Na, and SO₄ mixed into the conductivepaste are mixed into a semiconductor layer (particularly, a channelregion) of a TFT, defects occur to decrease TFT characteristics.Therefore, such impurities are desirably reduced to 10 ppm or less.

The nanopaste can be cured when being heated at a temperature of 220 to250° C. It is desirable that the cured silver nanopaste have aresistance of 1 to 5 μΩ·cm and a film thickness of 5 μm or less; and thecured gold nanopaste have a resistance of 1 to 10 μΩ·cm and a filmthickness of 1 μm or less. Further, both of the cured silver nanopasteand the cured gold nanopaste desirably have a metal content of 95 to 98wt %.

Used also as conductive particles is hybrid paste combining thenanopaste and general conductive paste that is produced by anelectrolytic method, an atomization method, wet reduction or the like.

A gate electrode layer may be formed by discharging a compositioncontaining particles in which one conductive material is covered withanother conductive material. In that case, a buffer layer is desirablyprovided between each conductive material. For example, in the particlestructure shown in FIG. 23A in which Cu 2310 is covered with Ag 2311, abuffer layer 2312 formed of Ni or NiB (nickel boron) may be providedbetween the Cu 2310 and the Ag 2311 (FIG. 23B).

When a gas mixed with oxygen having a partial pressure of 10 to 30% isused in the baking step of the composition containing a conductivematerial, the resistivity of a conductive film of the gate electrodelayer can be reduced and the conductive film can be reduced in thicknessand planarized. Note that a solvent in the composition is volatilized bydischarging the composition containing a conductive material under lowpressure, thereby the time for the heat treatment thereafter (drying orbaking) can be reduced.

In addition to the aforementioned drying and baking, treatment such aspress treatment for applying pressure while heating by a heater, rollertreatment, and CMP (Chemical Mechanical Polish) may be performed forfurther smoothing and planarizing the surface.

Note that the gate electrode 102 may be formed by applying a conductivefilm over an entire surface of the substrate in advance, and thenetching the conductive film using a mask pattern. At this time, the maskpattern is desirably formed by a droplet discharge method, thoughconventional exposure and development may also be adopted. The maskpattern is formed by selectively discharging on the conductive film anorganic composition containing acryl, benzocyclobutene, polyamide,polyimide, benzimidazole, or polyvinyl alcohol by a droplet dischargemethod. By using the droplet discharge method, the composition can bedischarged selectively to form a pattern only in a desired area.

Further, a composition containing a photosensitive agent may be used asa material of the mask pattern. For example, a composition in which anovolac resin that is a positive resist and a naphthoquinonediazidecompound that is a photosensitive agent, a base resin that is a negativeresist, diphenylsilanediol, and an acid generator; or the like aredissolved or dispersed in a known solvent may be used. Instead, amaterial having a backbone structure obtained by binding silicon (Si) tooxygen (O) and having at least a hydrogen substituent, or further havingone or more substituents selected from fluorine, an alkyl group, andaromatic hydrocarbon in addition to hydrogen (typically, siloxane-basedpolymer) may be used. It is desirable that the mask pattern is baked andcured before etching the conductive film.

In the case where the gate electrode 102 is formed by etching, the stepcoverage is preferably improved by tapering the gate electrode 102 inorder to avoid electrical connection with a semiconductor film 111formed later. The mask pattern is removed after the etching.

Used as the substrate 100 is a glass substrate, a quartz substrate, asubstrate made of an insulating substance such as alumina, a heatresistant plastic substrate which can endure the processing temperatureof the subsequent steps, or the like. In that case, it is desirable toform an insulating base film of silicon oxide (SiO_(x)), silicon nitride(SiN_(x)), silicon oxynitride (SiO_(x)N_(y)) (x>y), silicon nitrideoxide (SiN_(x)O_(y)) (x>y) (x, y=1, 2 . . . ), or the like in order toprevent diffusion of impurities or the like from the substrate. Further,as the substrate 100, a substrate made of metal such as stainless or asemiconductor substrate may be used by applying the surface thereof withan insulating film of silicon oxide or silicon nitride.

Subsequently, a gate insulating film 104 is formed over the gateelectrode 102. The gate insulating film 104 is preferably formed of asingle layer or multi layers of a film containing silicon nitride,silicon oxide, silicon nitride oxide, or silicon oxynitride by a thinfilm forming method such as plasma CVD and sputtering. In thisembodiment mode, a silicon nitride film (SiN_(x) film) 104 a, a siliconoxide film (SiO_(x) film) 104 b and a silicon nitride film (SiN_(x)film) 104 c are stacked over the substrate 100 in this order, though theinvention is not limited to these structure, material and method (FIG.2B).

Then, a semiconductor film 105 is formed over the gate insulating film104 (FIG. 2C). The semiconductor film 105 is formed of an amorphoussemiconductor, a crystalline semiconductor or a semi-amorphoussemiconductor, each of which mainly contains silicon, silicon germanium(Si_(x)Ge_(1-x)), or the like. The semiconductor film 105 may be formedby plasma CVD or the like. It is desirable that the semiconductor film105 have a thickness of 10 to 100 nm.

An SAS (semi-amorphous silicon, also called microcrystalline silicon)that is a kind of the aforementioned semi-amorphous semiconductor isbriefly described. The SAS can be obtained by glow dischargedecomposition of silicon gas. Typically, SiH₄ is used as a silicon gas,though Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄ or the like may be used aswell. The formation of the SAS can be facilitated by diluting thesilicon gas with a single or a plurality of noble gas elements selectedfrom hydrogen, hydrogen and helium, argon, krypton, and neon. Thesilicon gas is preferably diluted at a dilution rate of 10 to 1000. Itis needless to say that the formation of the SAS by glow dischargedecomposition is desirably performed under low pressure, but dischargemay be performed under a pressure of about 0.1 to 133 Pa. The powerfrequency for generating the glow discharge is in the range of 1 to 120MHz, and more preferably, an RF power of 13 to 60 MHz is supplied. Thesubstrate is preferably heated at a temperature of 300° C. or less, andmore preferably 100 to 200° C.

The silicon gas may also be mixed with a carbon gas such as CH₄ andC₂H₆, or a germanium gas such as GeH₄ and GeF₄ to set the energybandwidth at 1.5 to 2.4 eV, or 0.9 to 1.1. eV.

When an impurity element for controlling valence electrons is not addedto an SAS intentionally, the SAS exhibits a small N-type conductivity.This is because oxygen is easily mixed into a semiconductor film sincethe glow discharge is performed at a higher power than in the case offorming an amorphous semiconductor. When an impurity element thatimparts P-type conductivity is added to the semiconductor film includinga channel forming region of a TFT simultaneously with or after thedeposition, a threshold voltage can be controlled. Typically, boron isused for an impurity element that imparts P-type conductivity. Animpurity gas such as B₂H₆ and BF₃ may be mixed into the silicon gas at arate of 1 to 1000 ppm. For example, in the case of boron being used asan impurity element that imparts P-type conductivity, the concentrationof boron is preferably set at 1×10¹⁴ to 6×10¹⁶ atoms/cm³. Note that whena channel forming region is formed of such an SAS, a field effectmobility of 1 to 10 cm²/V·sec can be obtained.

A crystalline semiconductor film can be obtained by the following steps:an amorphous semiconductor film is treated with a solution containing acatalyst such as nickel; a crystalline silicon semiconductor film isobtained by thermal crystallization at a temperature of 500 to 750° C.;and the crystallinity of the crystalline semiconductor film is improvedby laser crystallization.

The crystalline semiconductor film can also be obtained by directlyforming a polycrystalline semiconductor film by LPCVD (Low Pressure CVD)using disilane (Si₂H₆) and germanium fluoride (GeF₄) as material gas. Inthis embodiment mode, the flow rate of the gas is set so thatSi₂H₆/GeF₄=20/0.9 is satisfied, the deposition temperature is set at 400to 500° C., and He or Ar is used as a carrier gas, though the inventionis not limited to these conditions.

Next, an insulating film 106 is formed over the semiconductor film 105(FIG. 2C). The insulating film 106 may be formed of a single layer ormulti layers of a film containing silicon nitride, silicon oxide,silicon nitride oxide, or silicon oxynitride. Alternatively, a resinsuch as polyimide, acryl and siloxane may be applied over an entiresurface.

A first mask pattern 107 is selectively formed using a resist or thelike. Then, the insulating film 106 is etched by wet etching or dryetching using the first mask pattern 107 as a mask, thereby a channelprotective film 108 is formed (FIG. 2D). It is desirable that the firstmask pattern 107 is selectively formed by a droplet discharge method,though it may be formed through conventional exposure and developmentsteps. Note that the first mask pattern 107 may be formed of aninsulating film such as acryl, benzocyclobutene, polyamide, polyimide,benzimidazole, and polyvinyl alcohol as well as a resist. The sameapplies to various mask patterns described below.

After removing the first mask pattern 107, an N-type semiconductor film109 is formed (FIG. 2E). The N-type semiconductor film 109 may be formedof an amorphous semiconductor, a crystalline semiconductor or asemi-amorphous semiconductor, each of which mainly contains silicon,silicon germanium (SiGe) or the like. As an N-type impurity element,arsenic (As) or phosphorous (P) can be used. The N-type semiconductorfilm 109 may be formed by plasma CVD or the like. For example, in thecase where the N-type semiconductor film 109 is formed of an SAS(semi-amorphous silicon), glow discharge decomposition of a mixed gas ofSiH₄, H₂ and PH₃ (phosphine) is performed by plasma CVD to obtain anN-type (n+) silicon film. Note that although the N-type semiconductorfilm is used herein, a P-type semiconductor film containing a P-typeimpurity element such as boron (B) may be used as well.

Although not shown, the N-type semiconductor film or the P-typesemiconductor film may be formed by doping an impurity element usinganother mask pattern as a mask. As the impurity element, boron (B) thatimparts P-type conductivity and arsenic (As) or phosphorous (P) thatimparts N-type conductivity may be employed. The impurity element may beadded by ion doping or ion injection. Note that the semiconductor filmmay be activated by heat treatment after the doping.

Subsequently, a second mask pattern 110 is selectively formed using aresist or the like. Then, the semiconductor film 105 and the N-typesemiconductor film 109 are etched by wet etching or dry etching usingthe second mask pattern 110 as a mask, thereby an island shapesemiconductor film 111, a source region 112 a and a drain region 112 bare formed (FIG. 3A). It is preferable that the second mask pattern 110is selectively formed by a droplet discharge method, though it may beformed through conventional exposure and development steps.

The island shape semiconductor film 111 and the source and drain regions112 a and 112 b are simultaneously formed in this embodiment mode.However, after an island shape semiconductor film and an island shapeN-type semiconductor film are formed using the second mask pattern 110,the island shape N-type semiconductor film may be removed by etchingusing another mask pattern to form the source and drain regions 112 aand 112 b.

When the N-type semiconductor film is removed by etching to form thesource and drain regions 112 a and 112 b, the channel protective film108 prevents a channel region 119 from being damaged due to over etchingand the like.

Although not shown, a passivation film may further be provided over thesource and drain regions 112 a and 112 b in order to prevent impuritiesfrom being mixed or diffused into the semiconductor film. Thepassivation film may be formed of silicon nitride, silicon oxide,silicon nitride oxide, silicon oxynitride, aluminum oxynitride, aluminumoxide, diamond like carbon (DLC), carbon nitride (CN), or otherinsulating materials. The material of the aforementioned mask patternmay be employed as well. Further, the passivation film may be formed ofa stack of these materials.

Next, an organic film 113 having liquid repellency to an interlayerinsulating film formed later is applied over an entire surface (FIG.3B). In this embodiment mode, fluoroalkyl silane (FAS) that is a kind ofa silane coupling agent is formed by slit coating, though the inventionis not limited to these material and forming method. Note that since theFAS is a monomolecular film, the thickness thereof is about a few nm.

Surface treatment using a silane coupling agent is now described. First,a silane coupling agent is selectively applied over an entire surface ofthe substrate or in an area in which at least the organic film is to beformed, by spin coating, slit coating or the like. Next, the silanecoupling agent is left under room temperature to be dried, and waterwashing is performed to remove an unnecessary agent. Finally, the silanecoupling agent is baked, so that siloxane network (a structure in whicha material has a backbone structure obtained by binding silicon (Si) tooxygen (O), which contains at least a hydrogen substituent, or furtherhas one or more substituents selected from fluorine, an alkyl group, andaromatic hydrocarbon in addition to hydrogen) including a CF₂ chain anda CF₃ chain is created. The drying and the water washing may be omitted.CF₂ and CF₃ allows the film whose surface is treated with the silanecoupling agent to have liquid repellency.

The silane coupling agent is a silicon compound represented byR_(n)—Si—X_(4-n) (n=1, 2, 3). Here, R denotes a substance that containsa relatively inert group such as an alkyl group or a reactive group suchas a vinyl group, an amino group and an epoxy group. Further, X isformed with halogen, a methoxy group, an ethoxy group, or a hydroxylgroup of the substrate surface such as an acetoxy group, or ahydrolysate group that is bondable with absorbed water by condensation.In particular, when R is an inert group such as an alkyl group, the filmsurface is provided with characteristics such as water repellency,resistance against adhesion and friction, lubricity, and luster. If n=1,the silicon compound is used as a coupling agent; if n=2, the siliconcompound is used as a material of a siloxane polymer; and if n=3, thesilicon compound is used as a silylating agent or a blocking agent of apolymer (an end cap agent for terminating each end of a polymer.) TheFAS used in this embodiment mode has a structure denoted by (CF₃)(CF₂)_(x) (CH₂)_(y) (x is an integer of 0 to 10 and y is an integer of 0to 4). In the case where a plurality of R or X are bonded to Si, R and Xmay be either the same or different.

The silane coupling agent is typified by a fluoroalkoxy silane couplingagent. For example, CF₃(CF₂) _(k)CH₂CH₂Si(OCH₃) ₃, CF₃(CF₂)_(k)CH₂CH₂SiCH₃(OCH₃) ₂, CF₃(CF₂) _(k)CH₂CH₂Si (OCH₂CH₃) ₃ (k=3, 5, 7,9); (CF₃) ₂CF(CF₂) _(m)CH₂CH₂Si(OCH₃) ₃, (CF₃) ₂CF(CF₂)_(m)CH₂CH₂SiCH₃(OCH₃) ₂ (m=4, 6, 8); and CF₃(CF₂) _(j) (C₆H₄) C₂H₄Si(OCH₃) ₃, CF₃(CF₂) _(j) (C₆H₄) C₂H₄SiCH₃ (OCH₃₎ ₂ (j=0, 3, 5, 7) aregiven as an example of the silane coupling agent. The silane couplingagent-is also typified by alkoxysilane having an alkyl group for R. Itis preferable to use alkoxysilane with a carbon number of 2 to 30. Therearc typically ethyltriethoxysilane, propyltriethoxysilane,octyltriethoxysilane, decyltriethoxysilane, octadecyltriethoxysilane(ODS), eicosyltriethoxysilane, and triacontyltriethoxysilane.

A structure of a glass surface in the case of surface modification ofglass that is an insulator being performed using CF₃ (CF₂) _(k)CH₂CH₂Si(OCH₃) ₃ is shown in FIG. 22. The contact angle with liquid (forexample, water) adhered onto the glass increases in the order ofCF<CF₂<CF₃. Further, the contact angle tends to be larger as the chainof fluorocarbon is longer. Note that the contact angle e is defined asan angle formed by a liquid surface and a solid surface in the areawhere the free surface of stationary liquid touches a solid surface. Thecontact angle depends on the magnitude relationship between cohesion ofliquid molecules and adherence between the liquid and the solid surface.The contact angle is acute when the liquid wets the solid (when theadherence is strong), and the contact angle is obtuse when the liquiddoes not wet the solid. In other words, as the contact angle is larger,the adherence is weaker, namely, the liquid repellency is increased.

Instead of FAS, as a fluorine-based resin having liquid repellency,polytetra-fluoroethylene (PTFE), perfluoroalkoxy alkane (PFA),perfluoro-ethylene-propylene copolymer (PFEP),ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride(PVDF), polychloro-trifluoroethylene (PCTFE),ethylene-chlorotrifluoroethylene copolymer (ECTFE),polytetrafluoroethylene-perfluoro dioxole copolymer (TFE/PDD), polyvinylfluoride (PVF), or the like can be used. Note that the organic film isregarded as having liquid repellency in a case the contact angle beingmore than 35° (more preferable 45°).

Note that the organic film 113 may be formed by plasma treatment using aCF₄ gas or a CHF₃ gas. In that case, a mixed gas diluted with a noblegas may be used as well. Further, other gases may also be employed aslong as they contain fluorine.

Subsequently, a third mask pattern 114 is selectively formed in an areain which a contact hole is to be formed between interlayer insulatingfilms (FIG. 3B). It is desirable that the third mask pattern 114 isselectively formed by a droplet discharge method. In this embodimentmode, the third mask pattern 114 is formed of PVA (polyvinyl alcohol),though the invention is not limited to this and other water solubleresins or organic resins such as polyimide, acryl and siloxane may beused for example.

Then, the organic film 113 is removed using the third mask pattern 114as a mask, thereby an island shape organic film 115 is formed (FIG. 3C).The organic film 113 is desirably removed by O₂ ashing or atmosphericpressure discharge plasma, though the invention is not limited to this.For example, UV ozone treatment, laser treatment or the like can beadopted.

The third mask pattern 114 formed of PVA is removed by H₂O (waterwashing) (FIG. 3C). Note that in the case of polyimide or acryl beingused, the third mask pattern 114 can be easily removed by the N300stripper or the 710 stripper. Needless to say, ashing or etching may beused as well for removing.

Although the third mask pattern 114 is removed in this embodiment mode,it may remain in the case of having liquid repellency to an interlayerinsulating film formed later. Even when the third mask pattern 114 doesnot have liquid repellency, it can be treated with CF₄ plasma or thelike to obtain liquid repellency. For example, when a water solubleresin such as PVA is treated with CF₄ plasma, it can obtain liquidrepellency to an organic resin such as polyimide, acryl and siloxaneused as an interlayer insulating film.

Next, an interlayer insulating film 116 formed of an organic resin isapplied over an entire surface of the substrate. Although a heatresistant siloxane resin is used here, the invention is not limited tothis and an organic resin such as polyimide and acryl may be used aswell. At this time, the interlayer insulating film 116 is not formedover the island shape organic film 115 since the island shape organicfilm 115 repels the organic resin. As a result, a contact hole 117 isformed in a self aligned manner (FIG. 3C). Further, the interlayerinsulating film 116 is tapered at this time, thus step coverage with aconductive film formed later can be improved. Note that the island shapeorganic film 115 is removed thereafter by O₂ ashing, atmosphericpressure plasma or the like. Instead, UV ozone treatment, lasertreatment or the like may also be performed.

Subsequently, a composition containing a conductive material isdischarged into the contact hole 117 by a droplet discharge method, thendried or baked to form a source wiring 118 a and a drain wiring 118 b(collectively referred to as a 2nd wiring) (FIG. 3D). The source wiring118 a and the drain wiring 118 b (the 2nd wiring) are connected to thesource and drain regions 112 a and 112 b of a TFT respectively. In thecase where a passivation film is formed over the source and drainregions 112 a and 112 b, it is removed by etching or the like using theinterlayer insulating film 116 as a mask to form the contact hole 117.The etching is desirably performed using an etchant having high etchselectivity relative to the semiconductor film constituting the sourceand drain regions on the bottom layer. The source and drain wirings 118a and 118 b may be formed of a similar conductive material to that usedfor the gate electrode.

Although the source and drain regions are directly connected to thesource and drain wirings in this embodiment mode, another conductivelayer (single layer or multi-layers) may be disposed therebetween.

In such a manner, a channel protected TFT can be obtained. Since thechannel protected TFT includes a channel protective film 108, it ispossible to prevent the channel region 119 from being damaged due toover etching when the N-type semiconductor film is etched to form thesource and drain regions. Thus, the channel protected TFT can havestable characteristics and high mobility.

Embodiment Mode 3

In this embodiment mode, a manufacturing method of a bottom gate TFTaccording to the invention, in particular a manufacturing method of achannel etched TFT is described with reference to FIGS. 4A to 4D andFIGS. 5E to 5G.

A gate electrode 402, a gate insulating film 404 and a semiconductorfilm 405 can be formed over a substrate 400 in the same manner as thatdescribed in Embodiment Mode 2 (see FIG. 4A and FIGS. 2A to 2C). In thisembodiment mode, the base film pretreatment such as the formation of atitanium oxide film is omitted. However, it is needless to say that thepretreatment may be performed similarly to Embodiment Mode 2. Further,although the gate insulating film 404 has a single layer structure, itmay have a multi-layer structure. Note that since a channel protectivefilm is not provided in this embodiment mode, a mask patterncorresponding to the first mask pattern in Embodiment Mode 2 is notrequired.

An N-type semiconductor film 409 is formed over the semiconductor film405, and then a mask pattern 420 (that corresponds to the second maskpattern in Embodiment Mode 2, and is referred to as a second maskpattern in this embodiment mode) is formed (FIG. 4A). The material andmanufacturing method of the N-type semiconductor film 409 and the secondmask pattern 420 may be the same as those shown in Embodiment Mode 2.Note that although the N-type semiconductor film is used herein, aP-type semiconductor film containing a P-type impurity element such asboron (B) may be used as well.

Next, etching is performed using the second mask pattern 420 as a mask,thereby an island shape semiconductor film 411 and an island shapeN-type semiconductor film 421 are formed (FIG. 4B).

Subsequently, a source electrode 422 and a drain electrode 423 areformed (FIG. 4C). The source and drain electrodes 422 and 423 aredesirably formed by discharging a composition containing a conductivematerial by a droplet discharge method and then drying or baking. Theconductive material can be arbitrarily selected from the materials thatare shown in Embodiment Mode 2 as conductive materials of the gateelectrode.

The island shape N-type semiconductor film 421 is etched using thesource and drain electrodes 422 and 423 as masks, thereby a sourceregion 412 a and a drain region 412 b are formed (FIG. 4D). At thistime, the etching rate, the time for treatment, and the like arerequired to be controlled in order to prevent the island shapesemiconductor film 411 including a channel region 419 of a TFT frombeing damaged.

Although not shown, a passivation film may further be provided over thesource and drain regions 412 a and 412 b in order to prevent impuritiesfrom being mixed into the semiconductor film. The passivation film maybe formed of a single layer or multi-layers of a film containing siliconnitride, silicon oxide, silicon nitride oxide, or silicon oxynitride.

Then, an organic film 413 having liquid repellency to an interlayerinsulating film formed later is applied over an entire surface of thesubstrate (FIG. 5A). In this embodiment mode, fluoroalkyl silane (FAS)is formed by spin coating or slit coating, though the invention is notlimited to these material and forming method. Note that since the FAS isa monomolecular film, the thickness thereof is about a few nm.

Note that the organic film 413 may be formed by plasma treatment using aCF₄ gas or a CHF₃ gas. In that case, a mixed gas diluted with a noblegas may be used as well. Further, other gases may also be employed aslong as they contain fluorine.

Then, a mask pattern 414 (that corresponds to the third mask pattern inEmbodiment Mode 2, and is referred to as a third mask pattern in thisembodiment mode) is selectively formed in an area in which a contacthole is to be formed between interlayer insulating films (FIG. 5A). Itis desirable that the third mask pattern 414 be selectively formed by adroplet discharge method. In this embodiment mode, the third maskpattern 414 is formed of PVA (polyvinyl alcohol), though the inventionis not limited to this and other water soluble resins or organic resinssuch as polyimide, acryl and siloxane may be used for example.

The organic film 413 is removed using the third mask pattern 414 as amask to form an island shape organic film 415 (FIG. 5B). The organicfilm 413 is desirably removed by O₂ ashing or atmospheric pressuredischarge plasma, though the invention is not limited to this. Forexample, UV ozone treatment, laser treatment or the like may be adoptedas well.

The third mask pattern 414 formed of PVA is removed by H₂O (waterwashing) (FIG. 5B). Note that in the case of polyimide or acryl beingused, the third mask pattern 414 can be easily removed by the N300stripper or the 710 stripper. Needless to say, ashing or etching may beused as well for removing.

Although the third mask pattern 414 is removed in this embodiment mode,it may remain in the case of having liquid repellency to an interlayerinsulating film formed later. Even when the third mask pattern 414 doesnot have liquid repellency, it can be treated with CF₄ plasma or thelike to obtain liquid repellency. For example, when a water solubleresin such as PVA is treated with CF₄ plasma, it can obtain liquidrepellency to an organic resin such as polyimide, acryl and siloxaneused as an interlayer insulating film.

Next, an interlayer insulating film 416 formed of an organic resin isapplied over an entire surface of the substrate. Although a heatresistant siloxane resin is used here, the invention is not limited tothis and an organic resin such as polyimide and acryl may be used aswell. At this time, the interlayer insulating film 416 is not formedover the island shape organic film 415 since the island shape organicfilm 415 repels the organic resin. As a result, a contact hole 417 isformed in a self-aligned manner (FIG. 5B). Further, the interlayerinsulating film 416 is tapered at this time, thus step coverage with aconductive film formed later can be improved. Note that the island shapeorganic film 415 is removed thereafter by O₂ ashing, atmosphericpressure plasma or the like.

A composition containing a conductive material is discharged into thecontact hole 417 by a droplet discharge method, then dried or baked toform a source wiring 418 a and a drain wiring 418 b (FIG. 5C). Thesource wiring 418 a and the drain wiring 418 b are connected to thesource and drain electrodes 422 and 423 of a In respectively. In thecase where a passivation film is formed over the source and drainelectrodes 422 and 423, it is removed by etching or the like using theinterlayer insulating film 416 as a mask to form the contact hole 417.The etching is desirably performed using an etchant having high etchselectivity relative to the source and drain electrodes on the bottomlayer. The source and drain wirings 418 a and 418 b may be formed of aconductive material arbitrarily selected from the materials that areshown in Embodiment Mode 2 as conductive materials of the gateelectrode.

In such a manner, a channel etched TFT can be obtained. The channeletched TFT has the advantages that a channel protective film is notrequired and forming steps of a mask pattern can be simplified.

Embodiment Mode 4

In this embodiment mode, a manufacturing method of a top gate TFTaccording to the invention is described with reference to FIGS. 6A to 6Dand FIGS. 7E to 7H.

First, a semiconductor film 605 is formed over a substrate 600 (FIG.6A). The semiconductor film 605 is formed of an amorphous semiconductor,a crystalline semiconductor or a semi-amorphous semiconductor, each ofwhich mainly contains silicon, silicon germanium (Si_(x)Ge_(1-x)) or thelike. The semiconductor film 605 may be formed by plasma CVD or thelike, and the thickness thereof is desirably in the range of 10 to 100mn.

An N-type semiconductor film 609 is formed over the semiconductor film605 (FIG. 6A). The N-type semiconductor film 609 is formed of anamorphous semiconductor, a crystalline semiconductor or a semi-amorphoussemiconductor, each of which mainly contains silicon, silicon germanium(Si_(x)Ge_(1-x)) or the like. As an N-type impurity element, arsenic(As) or phosphorous (P) may be used. The N-type semiconductor film 609may be formed by plasma CVD or the like. For example, in the case wherethe N-type semiconductor film 609 is formed of an SAS (semi-amorphoussilicon), glow discharge decomposition of a mixed gas of SiH₄, H₂ andPH₃ (phosphine) is performed by plasma CVD to obtain an N-type (n+)silicon film. Note that although the N-type semiconductor film is usedherein, a P-type semiconductor film containing a P-type impurity elementsuch as boron (B) may be used as well.

Next, a composition containing a conductive material is discharged froma nozzle over the N-type semiconductor film 609, thereby a sourceelectrode 624 and a drain electrode 625 are formed (FIG. 6A). The sourceand drain electrodes 624 and 625 are formed by drying the dischargedcomposition at a temperature of 100° C. for three minutes, and thenbaking it at a temperature of 200 to 350° C. for 15 to 30 minutes,though the invention is not limited to these conditions. In addition,although the composition containing Ag (hereinafter referred to as Agnanopaste) as a conductive material is discharged in this embodimentmode, the conductive material may be arbitrarily selected from thematerials that are shown in Embodiment Mode 2 as conductive materials ofthe gate electrode.

Note that the source and drain electrodes 624 and 625 may be formed bypatterning a conductive film that is formed by sputtering.

Subsequently, the N-type semiconductor film 609 is etched using thesource and drain electrodes 624 and 625 as masks, thereby a sourceregion 612 a and a drain region 612 b are formed (FIG. 6B). At thistime, the etching conditions are required to be controlled so as toprevent the semiconductor film 605 from being etched and removed.However, if the etching rate of a surface of the semiconductor film 605is small as shown in FIG. 6B, TFT characteristics are not seriouslydegraded.

A gate insulating film 604 is formed over the source and drainelectrodes 624 and 625 (FIG. 6C). It is preferable that the gateinsulating film 604 is b formed of a single layer or multi-layers of afilm containing silicon nitride, silicon oxide, silicon nitride oxide,or silicon oxynitride by a thin film forming method such as plasma CVDand sputtering. In this embodiment mode, a silicon nitride film isformed to have a thickness of 100 mm. In the case of a multi-layerstructure, a SiN_(x) film, a SiO_(x) film and a SiN_(x) film may bestacked in this order.

A mask pattern 626 is selectively formed using a resist or the like.Then, the gate insulating film 604 and the semiconductor film 605 areetched using the mask pattern 626 as a mask, thereby an island shapesemiconductor film 619 is formed (FIG. 6C). It is desirable that themask pattern 626 is selectively formed by a droplet discharge method,though it may be formed through conventional exposure and developmentsteps. The mask pattern 626 is removed thereafter.

The island shape semiconductor film 619 is formed after the source anddrain regions 612 a and 612 b are formed in this embodiment mode.Alternatively, an island shape semiconductor film and an island shapeN-type semiconductor film may be formed after the semiconductor film 605and the N-type semiconductor film 609 shown in FIG. 6A are formed, andthen the source and drain regions 612 a and 612 b may be formed usingthe source and drain electrodes 624 and 625 as masks. In that case, thegate insulating film 604 is not required to be etched.

Next, a composition containing a conductive material is discharged froma nozzle 627 over the gate insulating film 604, thereby a gate electrode628 is formed (FIG. 6D). The gate electrode 628 is formed by drying thedischarged composition at a temperature of 100° C. for three minutes,and then baking it at a temperature of 200 to 350° C. for 15 to 30minutes, though the invention is not limited to these conditions. Inaddition, although the Ag nanopaste is discharged as a conductivematerial in this embodiment mode, the conductive material may bearbitrarily selected from the materials that are shown in EmbodimentMode 2 as conductive materials of the gate electrode. Note that the formof the nozzle 627 is not limited to the one shown in FIG. 6D.

Although not shown, the aforementioned base film pretreatment may beapplied to an area over the gate insulating film 604, in which at leastthe gate electrode 628 is to be formed. According to this, theadhesiveness between the gate electrode 628 and the gate insulating film604 can be improved.

In addition, although not shown, a passivation film may further beprovided over the gate electrode 628 in order to prevent impurities frombeing mixed into the semiconductor film. The passivation film may beformed of a single layer or multi-layers of a film containing siliconnitride, silicon oxide, silicon nitride oxide, or silicon oxynitride.

Then, an organic film 613 having liquid repellency to an interlayerinsulating film formed later is applied over an entire surface of thesubstrate (FIG. 7A). In this embodiment mode, fluoroalkyl silane (FAS)is formed by slit coating, though the invention is not limited to thesematerials and forming method. Note that since the FAS is a monomolecularfilm, the thickness thereof is about a few nm.

Note that the organic film 613 may be formed by plasma treatment using aCF₄ gas or a CHF₃ gas. In that case, a mixed gas diluted with a noblegas may be used as well. Further, other gases may also be employed aslong as they contain fluorine.

Then, a mask pattern 614 (that corresponds to the third mask pattern inEmbodiment Modes 2 and 3) is selectively formed in an area in which acontact hole is to be formed between interlayer insulating films (FIG.7B). It is desirable that the mask pattern 614 is selectively formed bya droplet discharge method. In this embodiment mode, the mask pattern614 is formed of PVA (polyvinyl alcohol), though the invention is notlimited to this and other water soluble resins or organic resins such aspolyimide, acryl and siloxane may be used for example.

The organic film 613 is removed using the mask pattern 614 as a mask toform an island shape organic film 615 EGG 7B). The organic film 613 isdesirably removed by O₂ ashing or atmospheric pressure discharge plasma,though the invention is not limited to this. For example, UV ozonetreatment, laser treatment or the like may be adopted as well.

The mask pattern 614 formed of PVA is removed by H₂O (water washing)(FIG. 7C). Note that in the case of polyimide or acryl being used, themask pattern 614 can be easily removed by the N300 stripper or the 710stripper. Needless to say, ashing or etching may be used as well forremoving.

Although the mask pattern 614 is removed in this embodiment mode, it mayremain in the case of having liquid repellency to an interlayerinsulating film formed later. Even when the mask pattern 614 does nothave liquid repellency, it can be treated with CF₄ plasma or the like toobtain liquid repellency. For example, when a water soluble resin suchas PVA is treated with CF₄ plasma, it can obtain liquid repellency to anorganic resin such as polyimide, acryl and siloxane used as aninterlayer insulating film.

Next, an interlayer insulating film 616 formed of an organic resin isapplied over an entire surface of the substrate. Although a heatresistant siloxane resin is used here, the invention is not limited tothis and an organic resin such as polyimide and acryl may be used aswell. At this time, the interlayer insulating film 616 is not formedover the island shape organic film 615 since the island shape organicfilm 615 repels the organic resin. As a result, a contact hole 617 isformed in a self-aligned manner (FIG. 7C). Further, the interlayerinsulating film 616 is tapered at this time, thus step coverage with aconductive film formed later can be improved. Note that the island shapeorganic film 615 is removed thereafter by O₂ ashing, atmosphericpressure plasma or the like.

The exposed gate insulating film 604 is etched to be removed using theinterlayer insulating film 616 as a mask, thereby the contact hole 617is completed. Note that the gate insulating film 604 and the islandshape organic film 615 may be removed at a time.

Subsequently, a composition containing a conductive material isdischarged into the contact hole 617 by a droplet discharge method, thendried or baked to form a source wiring 618 a and a drain wiring 618 b(collectively referred to as a 2nd wiring) (FIG. 7D). The source wiring618 a and the drain wiring 618 b (the 2nd wiring) are connected to thesource and drain electrodes 624 and 625 of a TFT respectively. In thecase where a passivation film is formed over the source and drainelectrodes 624 and 625, it is removed by etching or the like using theinterlayer insulating film 616 as a mask to form the contact hole 617.The etching is desirably performed using an etchant having high etchselectivity relative to the source and drain electrodes on the bottomlayer. The source and drain wirings 618 a and 618 b may be formed of asimilar conductive material to that used for the gate electrode.

Although the source and drain regions are directly connected to thesource and drain wirings in this embodiment mode, another conductivelayer (single layer or multi-layers) may be disposed therebetween.

In such a manner, a top gate TFT (inverted staggered TFT herein) can beobtained. In this embodiment mode, the source and drain electrodes areformed by utilizing the forming method of a contact hole according tothe invention, then a contact hole is formed according to the invention,and further source and drain wirings are formed. However, a formingmethod of a TFT is not limited to the foregoing, and the source anddrain electrodes may also function as the wirings. In that case, thesource and drain wirings 118 a and 118 b are not required (FIG. 6Dcorresponds to a cross sectional view of the completed TFT). Further,the source and drain electrodes function as a so-called metal mask foretching an N-type semiconductor film.

The aforementioned manufacturing method of a TFT shown in FIGS. 6A to 6Dand FIGS. 7E and 7H has novel features such as the forming method of acontact hole and the formation of source and drain regions by separatingan N-type semiconductor film using source and drain electrodes as ametal mask. Therefore, the manufacturing method of a TFT shown in FIGS.6A to 6D and FIGS. 7E and 7H can provide a manufacturing method of asemiconductor device using a droplet discharge method, which is low incost and high in throughput and yield.

Embodiment 1

In this embodiment, a manufacturing method of an active matrix EL lightemitting device according to the invention is described with referenceto FIGS. 9A and 9B, FIGS. 10A and 10B, FIGS. 11A to 11E, and FIGS. 12Ato 12C.

In the case where a light emitting element having a layer containing anorganic or inorganic compound (typically, a light emitting elementutilizing electro luminescence (EL)) is driven by a thin film transistor(TFT), at least two transistors are generally used in a pixel region asshown in FIGS. 9A and 9B, which are a switching TFT and a driving TFTprovided for preventing variations in ON current of the switching TFT.

In the light emitting element, a light emitting layer which is a stackof layers containing organic or inorganic compounds having differentcarrier transporting characteristics is sandwiched between a pair ofelectrodes, and the light emitting layer is formed so that holes can beinjected from an electrode and electrons can be injected from the otherelectrode. The light emitting element uses a phenomenon in which holesinjected from an electrode and electrons injected from the otherelectrode are recombined to excite luminescent centers and light isproduced when the excited state returns to a ground state.

FIG. 9B is a circuit diagram in the case where a light emitting elementhas a forward staggered structure, namely a pixel electrode of a drivingTFT 1602 corresponds to a hole injection electrode (anode). Meanwhile,FIG. 10B is a circuit diagram in the case where a light emitting elementhas an inverted staggered structure, namely the pixel electrode of thedriving TFT 1602 corresponds to an electron injection electrode(cathode).

Reference numeral 1601 in FIG. 9B denotes a switching TFT forcontrolling ON/OFF of a current flowing to a pixel. A drain wiring (or asource wiring) of the switching TFT 1601 is connected to a gateelectrode layer 1609 of the driving TFT 1602 as shown in FIG. 9B. Sincea gate insulating film and a semiconductor layer are provided betweenthe gate electrode layer 1609 and 2nd wirings 1605 and 1608 (sourcewiring or drain wiring), the gate electrode layer 1609 of the drivingTFT 1602 is electrically connected to the drain wiring 1608 (or thesource wiring) of the switching TFT 1601 through an opening 1610 such asa contact hole (see FIG. 9A). Note that these reference numerals areidentical to those in FIGS. 10A and 10B. Reference numeral 1611 in FIGS.9A and 9B and FIGS. 10A and 10B denotes a capacitor of which theposition is not limited to the one shown in FIGS. 9A and 9B and FIGS.10A and 10B. Note that reference numeral 1607 denotes a power sourceline, 1606 denotes a gate line, 1603 denotes a light emitting element.

A light emitting device and a manufacturing method thereof according tothe invention are described with reference to FIGS. 11A to 11E. FIGS.11A to 11E show cross sectional structures along a line X-X′ (switchingTFT side) and a line Y-Y′ (driving TFT side) of FIGS. 9A and 9B or FIGS.10A and 10B.

First, a so-called photocatalytic substance such as titanium (Ti) andtitanium oxide (TiO_(x)) or a heat resistant resin such as polyimide,acryl and siloxane is formed in an area over a substrate 1100, in whichat least a gate electrode layer is to be formed (not shown).Alternatively, plasma treatment may be performed. According to suchpretreatment, it is possible to increase the adhesiveness between thesubstrate 1100 and conductive films (gate electrode layers 1101 and 1102herein) formed later by discharging a composition containing aconductive material. When titanium oxide is formed, light transmissivitycan be increased. Titanium oxide may be formed directly, or can beobtained by baking a titanium film simultaneously with the conductivefilms. It is also possible to use a photocatalytic substance such asstrontium titanate (SrTiO₃), cadmium selenide (CdSe), potassiumtantalate (KTaO₃), cadmium sulfide (CdS), zirconium oxide (ZrO₂),niobium oxide (Nb₂O₅), zinc oxide (ZnO), iron oxide (Fe₂O₃), andtungsten oxide (WO₃) as well as titanium and titanium oxide. Theaforementioned pretreatment is desirably performed in order to increasethe adhesiveness between the substrate and the conductive films.

A composition containing a first conductive material is discharged overthe substrate 1100, or in the case of the pretreatment being performed,over an area in which the pretreatment is applied. Accordingly, the gateelectrode layer 1101 of the switching TFT and the gate electrode layer1102 of the driving TFT are formed. The gate electrode layer here meansa single layer or multi-layers of a conductor, which includes at least agate electrode portion of a TFT. The gate electrode layer is formed bydrying the discharged composition at a temperature of 100° C. for threeminutes, then baking it at a temperature of 200 to 350° C. for 15 to 30minutes under a nitrogen or oxygen atmosphere, though the conditions arenot limited to these.

Various materials may be selected as the first conductive materialdepending on the function of the conductive film. Typically used for thefirst conductive material is silver (Ag), copper (Cu), gold (Au), nickel(Ni), platinum (Pt), chromium (Cr), tin (Sn), palladium (Pd), iridium(Ir), rhodium (Rh), ruthenium (Ru), rhenium (Re), tungsten (W), aluminum(Al), tantalum (Ta), indium (In), tellurium (Te), molybdenum (Mo),cadmium (Cd), zinc (Zn), iron (Fe), titanium (Ti), silicon (Si),germanium (Ge), zirconium (Zr), barium (Ba), antimony lead, tin oxideantimony, fluoride doped zinc oxide, carbon, graphite, glassy carbon,lithium, beryllium, sodium, magnesium, potassium, calcium, scandium,manganese, gallium, niobium, sodium-potassium alloys, magnesium-coppermixtures, magnesium-silver mixtures, magnesium-aluminum mixtures,magnesium-indium mixtures, aluminum-aluminum oxide mixtures,lithium-aluminum mixtures, or the like, or silver halide particles,dispersed nanoparticles, indium tin oxide (ITO) used as a transparentconductive film, zinc oxide (ZnO), zinc oxide added with gallium (GZO),indium zinc oxide (IZO) in which 2 to 20% of zinc oxide is mixed intoindium oxide, organic indium, organotin, titanium nitride, or the like.

In addition, silicon (Si) or silicon oxide (SiOx) may be mixed into theaforementioned conductive material especially when used for atransparent conductive film. For example, a conductive material in whichsilicon oxide is contained in ITO (generally referred to as ITO—SiO_(x);however, hereinafter referred to as ITSO or NITO for convenience) may beused. Further, layers of these conductive materials may be stacked toform a desired conductive film.

The diameter of a nozzle used as a droplet discharge means is set at 0.1to 50 μm (preferably, 0.6 to 26 μm), and the amount of the compositiondischarged from the nozzle is set at 0.00001 to 50 pl (preferably,0.0001 to 10 pl). The discharge amount increases in proportion to thediameter of the nozzle. Further, the distance between an object and anorifice of the nozzle is preferably as short as possible, and reduced toabout 0.1 to 2 mm in order to discharge the composition on a desiredarea

The composition discharged from an orifice is preferably used a solutionin which gold, silver or copper is dissolved or dispersed in a solventin view of the resistivity. More preferably, silver or copper that haslow resistance may be used. Note that, in the case of copper being used,it is preferable to provide a barrier film for preventing impuritiesfrom entering. Used as the solvent may be esters such as butyl acetateand ethyl acetate, alcohols such as isopropyl alcohol and ethyl alcohol,or an organic solvent such as methyl ethyl ketone and acetone. As thebarrier film in the case of copper being used for a wiring, aninsulating or conductive material containing nitrogen such as siliconnitride, silicon oxynitride, aluminum nitride, titanium nitride, andtantalum nitride (TaN) may be employed, and such a material may beapplied by a droplet discharge method.

The viscosity of a composition used in the droplet discharge method ispreferably 300 mPa·s or less for preventing drying and allowing thecomposition to be discharged smoothly from the orifice. The viscosity ofthe composition, the surface tension, or the like may be setappropriately in accordance with the solvent or the application. Forexample, the viscosity of a composition in which ITO, ITSO, organicindium, or organotin is dissolved or dispersed in a solvent is 5 to 50mPa·s; the viscosity of a composition in which silver is dissolved ordispersed in a solvent is 5 to 20 mPa·s; and the viscosity of acomposition in which gold is dissolved or dispersed in a solvent is 10to 20 mPa·s.

It is preferable that the diameter of the conductor particles is assmall as possible in order to prevent each nozzle from clogging or tomake fine patterns, and more preferably, each particle has a diameter of0.1 μm or less, though it depends on the diameter of each nozzle or thedesirable pattern shape. Each composition may be formed by a knownmethod such as an electrolytic method, an atomization method and wetreduction, and the particle size is generally about 0.5 to 10 μm. Notethat, in the case of the composition being formed by gas evaporation,nanoparticles protected with a dispersant are as fine as about 7 nm, andthe nanoparticles are dispersed stably at a room temperature and behavesimilarly to liquid without aggregation in a solvent when they are eachprotected with a coating. Therefore, it is preferable to use a coating.

The gate electrode layer may be formed by discharging a compositioncontaining particles in which one conductive material is covered withanother conductive material. In that case, a buffer layer is desirablyprovided between each conductive material. For example, in the particlestructure in which Cu is covered with Ag, a buffer layer formed of Ni orNiB (nickel boron) may be provided between the Cu and the Ag.

When a gas mixed with oxygen having a partial pressure of 10 to 30% isused for the baking step of a composition containing a conductivematerial, the resistivity of a conductive film constituting the gateelectrode layer can be reduced and the conductive film can be reduced inthickness and planarized. Nanopaste containing a conductive materialsuch as Ag is an organic solvent dispersed or dissolved with aconductive material. However, the nanopaste also includes a dispersantor a thermosetting resin called a binder. In particular, the binderfunctions to prevent cracks or uneven baking from being produced duringbaking. Further, through drying or baking steps, evaporation of anorganic solvent, elimination of the dispersant by dissolution, andcuring and shrinking of the binder all proceed simultaneously, therebynanoparticles are fused to cure the nanopaste. At this time,nanoparticles grow to be several tens to one hundred and several tens nmin diameter, thereby adjacent grown particles are fused to be linkedtogether, forming a metallic bond. On the other hand, most of theremnant organic component (about 80 to 90%) is pushed out of themetallic bond, and consequently, a conductive film containing themetallic bond is formed as well as a film containing an organiccomponent that covers the exterior of the conductive film. The filmcontaining an organic component can be removed when oxygen contained ina gas reacts with carbon or hydrogen contained in the film containing anorganic component in the baking of the nanopaste under a nitrogen oroxygen atmosphere. In the case where oxygen is not contained in thebaking atmosphere, the film containing an organic component can beremoved by oxygen plasma treatment or the like. In this manner, the filmcontaining an organic component can be removed by baking the nanopasteunder a nitrogen or oxygen atmosphere or by oxygen plasma treatmentafter the baking. Thus, the conductive film containing the remnantmetallic bond can be planarized and reduced in thickness andresistivity.

A solvent in the composition containing a conductive material isvolatilized by discharging the composition under low pressure.Consequently, the time for heat treatment thereafter (drying or baking)can be reduced.

In addition to the aforementioned drying and baking steps, CMP (ChemicalMechanical Polish), a method of planarizing a conductive film by etchingan insulating film with planarity formed over the conductive film(called an etch back method), or the like may be performed for furthersmoothing and planarizing the surface.

Used as the substrate 1100 is a glass substrate, a quartz substrate, asubstrate made of an insulating substance such as alumina, a heatresistant plastic substrate which can endure the processing temperatureof the subsequent steps, or the like. In that case, it is desirable toform an insulating base film of silicon oxide (SiO_(x)), silicon nitride(SiN_(x)), silicon oxynitride (SiO_(x)N_(y)) (x>y), silicon nitrideoxide (SiN_(x)O_(y)) (x>y) (x, y=1, 2 . . . ), or the like in order toprevent diffusion of impurities or the like from the substrate. Further,as the substrate 1100, a substrate made of metal such as stainless or asemiconductor substrate may be used by applying the surface thereof withan insulating film of silicon oxide or silicon nitride.

Subsequently, a gate insulating film 1103 is formed over the gateelectrode layers 1101 and 1102. The gate insulating film 1103 ispreferably formed of a single layer or multi-layers of a film containingsilicon nitride, silicon oxide, silicon nitride oxide, or siliconoxynitride by a thin film forming method such as plasma CVD andsputtering, In this embodiment, a silicon oxide film, a silicon nitridefilm and a silicon oxide film are stacked over the substrate 1100 inthis order, though the invention is not limited to these structure,material and method.

Then, a semiconductor film is formed over the gate insulating film 1103.The semiconductor film is formed of an amorphous semiconductor, acrystalline semiconductor or a semi-amorphous semiconductor, each ofwhich mainly contains silicon, silicon germanium (SiGe), or the like.The semiconductor film may be formed by plasma CVD or the like. It isdesirable that the semiconductor film have a thickness of 10 to 100 nm.

An SAS (semi-amorphous silicon) that is a kind of the aforementionedsemi-amorphous semiconductor is briefly described. The SAS can beobtained by glow discharge decomposition of silicon gas. Typically, SiH₄is used as a silicon gas, and Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄ or thelike may be used as well. The formation of the SAS can be facilitated bydiluting the silicon gas with a single or a plurality of noble gaselements selected from hydrogen, hydrogen and helium, argon, krypton,and neon. The silicon gas is preferably diluted at a dilution rate of 10to 1000. It is needless to say that the reactive formation of the SAS byglow discharge decomposition is desirably performed under low pressure,but the discharge may be performed under a pressure of about 0.1 to 133Pa. The power frequency for generating the glow discharge is in therange of 1 to 120 MHz, and more preferably, an RF power of 13 to 60 MHzis supplied. The substrate is preferably heated at a temperature of 300°C. or less, and more preferably 100 to 200° C.

The silicon gas may also be mixed with a carbon gas such as CH₄ andC₂H₆, or a germanium gas such as GeH₄ and GeF₄ to set the energybandwidth at 1.5 to 2.4 eV, or 0.9 to 1.1 eV.

When an impurity element for controlling valence electrons is not addedto an SAS intentionally, the SAS exhibits a small N-type conductivity.This is because oxygen is easily mixed into a semiconductor film sincethe glow discharge is performed at a higher power than in the case offorming an amorphous semiconductor. When an impurity element whichimparts P-type conductivity is added to the first semiconductor filmincluding a channel forming region of a TFT simultaneously with or afterthe deposition, a threshold value can be controlled. Typically, boron isused for an impurity element that imparts P-type conductivity. Animpurity gas such as B₂H₆ and BF₃ may be mixed into the silicon gas at arate of 1 to 1000 ppm. For example, in the case of boron being used asan impurity element that imparts P-type conductivity, the concentrationof boron is preferably in the range of 1×10¹⁴ to 6×10¹⁶ atoms/cm³. Notethat when a channel forming region is formed of such an SAS, a fieldeffect mobility of 1 to 10 cm²/V·sec can be obtained.

A crystalline semiconductor film can be obtained by the following steps:an amorphous semiconductor film is treated with a solution containingnickel or the like; a crystalline silicon semiconductor film is obtainedby thermal crystallization at a temperature of 500 to 750° C.; and thecrystallinity of the crystalline semiconductor film is improved by lasercrystallization.

The crystalline semiconductor film can also be obtained by directlyforming a polycrystalline semiconductor film by LPCVD (Low Pressure CVD)using disilane (Si₂H₆) and germanium fluoride (GeF₄) as material gas. Inthis embodiment, the flow rate of the gas is set so thatSi₂H₆/GeF₄=20/0.9 is satisfied, the deposition temperature is set at 400to 500° C., a or Ar is used as a carrier gas, though the invention isnot limited to these conditions.

Next, an N-type semiconductor film is formed over the semiconductorfilm. As an N-type impurity element, arsenic (As) or phosphorous (P) maybe used. For example, in the case where an N-type semiconductor film isformed, glow discharge decomposition of a mixed gas of SiH₄, H₂ and PH₃(phosphine) is performed by plasma CVD to obtain an N-type (n+) siliconfilm. Note that instead of the N-type semiconductor film, a P-typesemiconductor film containing a P-type impurity element such as boron(B) may be used as well.

A composition containing a second conductive material is discharged overthe N-type semiconductor film, thereby source electrodes 1106 and 1130and drain electrodes 1107 and 1140 are formed. The second conductivematerial, the conductive particle structure, discharge conditions,drying and baking conditions, and the like thereof may be arbitrarilyselected from those for the first conductive material shown above. Notethat the first conductive material and the second conductive materialmay have the same particle structure or different particle structures.

Although not shown, pretreatment may be applied to the N-typesemiconductor film before discharging the composition containing asecond conductive material. According to this, the adhesiveness betweenthe N-type semiconductor film and the source and drain electrodes can beincreased. This pretreatment may be performed similarly to thepretreatment in the formation of the gate electrode layer, though aconductive material is required to be used.

Subsequently, the N-type semiconductor film is etched using the sourceand drain electrodes 1106, 1130, 1107 and 1140 as masks, thereby sourceregions 1110 and 1112 and drain regions 1111 and 1113 are formed. Inthis embodiment, plasma etching is performed using as an etching gaschlorine-based gas such as Cl₂, BCl₃, SiCl₄, or CCl₄, fluorine-based gassuch as CF₄, SF₆, NF₃, and CHF₃, or O₂, though the invention is notlimited to this. The etching may be performed by utilizing anatmospheric plasma using as an etching gas a mixed gas of CF₄ and O₂.Note that the etching rate, the time for etching, and the like arerequired to be controlled so as not to remove the semiconductor film byetching the N-type semiconductor film. However, even when thesemiconductor film is etched partially as shown in FIG. 11A, sufficientmobility of a TFT can be achieved when the thickness of thesemiconductor film in a channel region is 5 nm (50 Å) or more,preferably 10 nm (100 Å) or more, and more preferably 50 nm (500 Å) ormore.

An insulating film 1115 is formed by a droplet discharge method over anarea that is to be a channel region of the semiconductor film. Since theinsulating film 1115 functions as a channel protective film, adischarged composition is selected from a heat resistant resin such assiloxane or an insulating material that is resistant to etching such asacryl, benzocyclobutene, polyamide, polyimide, benzimidazole, andpolyvinyl alcohol. Preferably, siloxane or polyimide is employed. It isalso desirable that the insulating film 1115 have a thickness of 100 nmor more, and more preferably 200 nm or more in order to protect thechannel region from over etching. Therefore, although not shown, theinsulating film 1115 may be formed so as to be elevated over the sourceand drain electrodes.

The semiconductor film is etched using the source and drain electrodes1106, 1130, 1107 and 1140 and the insulating film 1115 as masks, therebyisland shape semiconductor films 1116 and 1118 are formed. In thisembodiment, plasma etching is performed using as an etching gaschlorine-based gas such as Cl₂, BCl₃, SiCl₄, or CCl₄, fluorine-based gassuch as CF₄, SF₆, NF₃, and CHF₃, or O₂, though the invention is notlimited to this. The etching may be performed by utilizing anatmospheric plasma using as an etching gas a mixed gas of CF₄ and O₂.Since the insulating film 1115 of the channel protective film is formedover the channel region in the island shape semiconductor film, thechannel region is not damaged due to over etching in the etching step.Accordingly, a channel protected (channel stopper) TFT having stablecharacteristics and high mobility can be obtained without using a resistmask.

Further, a composition containing a third conductive material isdischarged on the source and drain electrodes 1106, 1130, 1107 and 1140,thereby source and drain wirings 1121 to 1123 are formed. At this time,a wiring 1120 is formed simultaneously with the source and drain wirings1121 to 1123. The wiring 1120 functions as a mask for forming a contacthole between a gate and a drain as well as a wiring between the gale andthe drain.

The third conductive material, the conductive particle structure,discharge conditions, drying and baking conditions, and the like thereofmay be arbitrarily selected from those for the first conductive materialshown above. Note that the second conductive material and the thirdconductive material may have the same particle structure or differentparticle structures. A pixel electrode is desirably formed by a dropletdischarge method using a transparent conductive film such as ITO, ITSO,ZnO, GZO, IZO, organic indium, and organotin.

Although not shown, pretreatment for increasing the adhesiveness withthe bottom layer may be performed also in the formation of the sourceand drain wirings 1121 to 1123. This pretreatment may be performedsimilarly to the pretreatment in the formation of the gate electrodelayers 1101 and 1102.

Next, the gate insulating film 1103 is etched to be removed using thewirings 1120 and 1122 as masks, thereby a contact hole is formed. Inthis embodiment, plasma etching is performed using as an etching gaschlorine-based gas such as Cl₂, BCl₃, SiC₄, or CCl₄, fluorine-based gassuch as CF₄, SF₆, NF₃, and CHF₃, or O₂, though the invention is notlimited to this. The etching may be performed by utilizing anatmospheric plasma. Then, a composition containing a fourth conductivematerial is discharged to fill the contact hole, and a conductor 1125for connecting the gate and the drain is formed. The fourth conductivematerial, the conductive particle structure, discharge conditions,drying and baking conditions, and the like thereof may be arbitrarilyselected from those for the first conductive material shown above. Notethat the third conductive material and the fourth conductive materialmay have the same particle structure or different particle structures.

Although not shown, a passivation film is desirably formed over thesource and drain wirings 1121 to 1123 in order to prevent diffusion ofimpurities from above the TFT. The passivation film may be formed ofsilicon nitride, silicon oxide, silicon nitride oxide, siliconoxynitride, aluminum oxynitride, aluminum oxide, diamond like carbon(DLC), carbon nitride (CN), or other insulating materials by a thin filmforming method such as plasma CVD and sputtering. Instead, the samematerial as that of the channel protective film may be used, or a stackof these materials may also be used. Alternatively, the passivation filmmay be formed by discharging a composition containing insulatingmaterial particles by a droplet discharge method.

Subsequently, a liquid repellent material 1162 is formed over the sourceand drain electrodes of the TFT by a droplet discharge method, spincoating, slit coating, spray coating or the like. Then, a mask 1163formed of PVA, polyimide or the like is formed in an area in which acontact hole is to be formed (see FIG. 11A). The liquid repellentmaterial 1162 may be formed of a fluorine-based silane coupling agentsuch as FAS (fluoroalkyl silane). The mask 1163 may be formed byselectively discharging PVA, polyimide or the like by a dropletdischarge method.

The liquid repellent material 1162 is removed using the mask 1163 of PVAor the like (FIG. 11B). The liquid repellent material 1162 may beremoved by O₂ ashing or atmospheric pressure plasma. The mask 1163 isremoved thereafter by water washing in the case of PVA, or by the N300stripper or the like in the case of polyimide.

A planarizing film 1151 is formed by a droplet discharge method, spincoating or the like while leaving the liquid repellent material 1162 inan area in which the contact hole is to be formed (FIG. 11C). At thistime, the planarizing film 1151 is not formed over the area in which acontact hole is to be formed since the liquid repellent material 1162 isapplied thereon. In addition, the contact hole is not inverted tapered.It is preferable that the planarizing film 1151 is selectively formed bya droplet discharge method using an organic resin such as acryl,polyimide and polyamide, or an insulating film containing asiloxane-based material and including a Si—O bond and a Si—CH_(x) bond.After forming the planarizing film 1151, the liquid repellent material1162 is removed by O₂ ashing or atmospheric pressure plasma. In the casewhere a passivation film is provided, it is removed as well.

A pixel electrode 1126 connected to the source electrode or the drainelectrode through the contact hole is formed over the planarizing film1151 by a droplet discharge method (FIG. 11D). The material of the pixelelectrode 1126 is selected from a transparent conductive material suchas ITO and ITSO or a reflective conductive material such as MgAgdepending on whether the pixel electrode 1126 transmits light or not. Inthe case of the pixel electrode 1126 being formed of ITO or ITSO,luminous efficiency can be improved by forming a barrier film 1150formed of a silicon nitride film.

A bank 1127 formed of an organic resin film or an inorganic insulatingfilm is selectively formed over the pixel electrode 1126 by a dropletdischarge method. The bank 1127 is desirably formed of a heat resistantresin such as siloxane or a resin such as polyimide and acryl.Especially when siloxane is used, the subsequent vacuum baking can beperformed at a high temperature, thereby moisture adversely affecting anEL element can be removed sufficiently. Note that the bank 1127 isselectively formed to have an opening in which the pixel electrode 1126is exposed. This opening may be formed by using the forming method of acontact hole according to the invention.

An organic compound layer 1128 (electro luminescent layer) is formed soas to be in contact with the pixel electrode 1126 in the opening of thebank 1127. The organic compound layer 1128 may have a single layerstructure or a multi-layer structure. In the case of a multi-layerstructure, each layer is stacked over a semiconductor element (pixelelectrode) in such an order: (1) an anode, a hole injection layer, ahole transporting layer, a light emitting layer, an electrontransporting layer, and a cathode; (2) an anode, a hole injection layer,a light emitting layer, an electron transporting layer, and a cathode;(3) an anode, a hole injection layer, a hole transporting layer, a lightemitting layer, an electron transporting layer, an electron injectionlayer, and a cathode; (4) an anode, a hole injection layer, a holetransporting layer, a light emitting layer, a hole blocking layer, anelectron transporting layer, and a cathode; or (5) an anode, a holeinjection layer, a hole transporting layer, a light emitting layer, ahole blocking layer, an electron transporting layer, an electroninjection layer, and a cathode. Such a structure is a so-called forwardstaggered structure, and the pixel electrode 1126 functions as an anode.On the other hand, a structure in which a cathode is disposed closer toa semiconductor element (pixel electrode) than an anode is called aninverted staggered structure, and the pixel electrode 1126 functions asa cathode.

In the case of a forward staggered structure, an electron injectionelectrode 1129 (cathode) is formed so as to cover the organic compoundlayer 1128. Meanwhile, an anode is formed in the case of an invertedstaggered structure. The electron injection electrode 1129 may be formedof a known material with low work function such as Ca, Al, CaF, MgAg,and AlLi. An overlapping area of the hole injection electrode (pixelelectrode) 1126, the organic compound layer 1128 and the electroninjection electrode 1129 in the opening of the bank 1127 corresponds toa light emitting element (FIG. 11E).

Practically, the element completed up to the state shown in FIG. 11E ispreferably packaged (sealed) with an airtight protective film withlittle degasification (laminate film, UV curable resin film or the like)in order not to be exposed to the outside air. In this embodiment, theelement is sealed with a sealing substrate 1153 with an insulator 1152interposed therebetween.

Through the aforementioned steps, an EL light emitting device iscompleted. Note that the structure of a TFT used in the EL lightemitting device is not limited to the one shown in this embodiment.

The EL light emitting device of this embodiment can be applied to eachof a top emission light emitting device shown in FIG. 12A, a bottomemission light emitting device shown in FIG. 12B, and a dual emissionlight emitting device shown in FIG. 12C.

First, a dual emission light emitting device is described. In that case,a hole injection electrode 1226 may be formed of a transparentconductive film such as ITO, ITSO, ZnO, IZO, and GZO. When ITSO is usedas the anode (hole injection electrode) 1226, an ITSO layer containingsilicon oxide with different concentration may be stacked. Morepreferably, ITSO on the bottom layer (source or drain wiring side)contains silicon oxide with low concentration, whereas ITSO on the upperlayer (light emitting layer side) contains silicon oxide with highconcentration. According to this, the efficiency of hole injection intoan EL layer can be improved while maintaining low resistance of theconnection with a TFT. Needless to say, the anode 1226 may bemulti-layers of ITSO and other materials (e. g., a multi-layer structureof ITO on the bottom layer and ITSO on the upper layer), or multi-layersof other materials.

Meanwhile, a thin aluminum film, an aluminum film containing a minuteamount of Li, or the like with a thickness of 1 to 10 nm is used for acathode 1243 in order to transmit light from a light emitting layer.Thus, a dual emission light emitting device in which light from a lightemitting element 1246 can be emitted to the top and bottom sides can beobtained (FIG. 12C). Note that reference numeral 1245, 1241, 1242 and1244 denote a sealing substrate, a bank, an organic compound layer andan insulator respectively.

Even when the cathode 1243 is formed of the same material as that of theanode 1226, namely a transparent conductive film such as ITO and ITSO, adual emission light emitting device can be obtained. In that case, thetransparent conductive film may be a film containing silicon or siliconoxide, or may be multi-layers thereof.

Next, a top emission light emitting device is described with referenceto FIG. 12A. In general, a top emission light emitting device in whichlight from the light emitting element can be emitted to the oppositeside of the substrate (a top side) can be obtained by replacing theanode (hole injection electrode) 1226 and the cathode (electroninjection electrode) 1243 in a bottom emission type shown in FIG. 12Bwith each other, stacking the organic compound layer in reverse, andreversing the polarity of the current control TFT (an n-channel TFTherein). In the case where the electrodes and the organic compound layerare stacked in reverse as shown in FIG. 12A, a multi-layer structure oflight transmitting conductive oxide layers each containing silicon oxidewith different concentration is used as the hole injection electrode1226. Accordingly, a light emitting device with high stability can beobtained due to the advantageous effects such as improvements inluminous efficiency and low power consumption. Here, a reflective metalelectrode or the like may be used as the electron injection electrode(cathode) 1243.

Note that a top emission light emitting device can be obtained withoutexchanging the hole injection electrode 1226 and the electron injectionelectrode 1243 in the bottom emission type shown in FIG. 12B by applyinga transparent conductive film such as ITO and ITSO to the electroninjection electrode (cathode) 1243. The transparent conductive film usedfor the cathode may be a film containing silicon or silicon oxide, ormay be multi-layers thereof.

This embodiment can be implemented in combination with other embodimentmodes and embodiments.

Embodiment 2

An EL TV set can be completed using an EL display module manufacturedaccording to Embodiment 1. FIG. 13 is a block diagram showing the mainconfiguration of an EL TV set. The invention can be applied to any kindof EL display panel: a display panel in which only a pixel portion isformed over the display panel, and a scan line driver circuit 903 and asignal line driver circuit 902 are mounted thereto by TAB; a displaypanel in which a pixel portion as well as the scan line driver circuit903 and the signal line driver circuit 902 at the periphery thereof aremounted over the display panel by COG; and a display panel in which apixel portion and the scan line driver circuit 903 are integrally formedover a substrate by using TFTs formed of SAS, and the signal line drivercircuit 902 is mounted thereto as a driver IC. Note that referencenumeral 901 denotes an EL display panel.

Other external circuits include, at a video signal input side, a videosignal amplifier circuit 905 for amplifying a video signal received by atuner 904, a video signal processing circuit 906 for converting theamplified signal into a color signal corresponding to each color of red,green and blue, a control circuit 907 for converting the video signal soas to be inputted to a driver IC, and the like. The control circuit 907outputs a signal to each of the scan line side and the signal line side.In the case where the EL display module is driven in a digital manner, aconfiguration in which an input digital signal is divided into m signalsto be supplied may be adopted by providing a signal divider circuit 908in the signal line side.

An audio signal received by the tuner 904 is transmitted to an audiosignal amplifier circuit 909, an output of which is supplied to aspeaker 913 through an audio signal processing circuit 910. A controlcircuit 911 receives receiving station (received frequency) data andvolume control data from an input portion 912, and transmits the signalsto the tuner 904 or the audio signal processing circuit 910.

By incorporating the EL module including such external circuits into ahousing, a TV set as shown in FIG. 25A can be completed. The TV setincludes a display screen structured by the EL display module, aspeaker, an operating switch and the like. In this manner, a TV set canbe completed according to the invention.

It is needless to say that the invention can be applied to variousapparatuses other than the TV set, such as a monitor of a personalcomputer, and in particular a large display medium such as aninformation display-panel in the station or the airport, and anadvertisement board on the street.

Embodiment 3

In this embodiment, a manufacturing method of an active matrix liquidcrystal display device according to the invention is described withreference to FIG. 14 and FIGS. 15A to 15C.

FIG. 14 is a top plan view of one pixel of a liquid crystal displaydevice. Reference numeral 1401 denotes a switching TFT that controlsON/OFF of a current flowing to the pixel. In this embodiment, a singlegate TFT is adopted, however the invention is not limited to this. Amulti-gate TFT may be adopted. Reference numeral 1405 denotes a sourceor drain wiring (also called a 2nd wiring, a 2nd metal or the like)whereas 1413 denotes a capacitor wiring, and a capacitor 1411 is formedbetween the capacitor wiring 1413 and a pixel electrode 1403. Note thatthe position of the capacitor 1411 is not limited to the area shownhere. Reference numeral 1406 denotes a gate wiring.

A liquid crystal display device and a manufacturing method thereofaccording to the invention are described with reference to FIGS. 15A to15C. FIGS. 15A to 15C show cross sectional structures along a line Z-X(driving TFT side) and a line X-Y (switching TFT side) of FIG. 14.

The structure and manufacturing method of a TFT shown in FIGS. 15A to15C are similar to those shown in Embodiment 1 (see FIG. 11A). Note thatin this embodiment, a terminal wiring 1540 is formed simultaneously withgate electrode layers 1501 and 1502. A gate insulating film 1503 at theterminal is removed using a metal mask 1541, thereby a contact hole isformed. The contact hole is filled with a conductor to form a terminalelectrode 1542. Needless to say, the contact hole may be formedaccording to the invention.

Although not shown, a passivation film is desirably formed over thesource and drain wirings in order to prevent diffusion of impuritiesfrom above the TFT; The passivation film may be formed of siliconnitride, silicon oxide, silicon nitride oxide, silicon oxynitride,aluminum oxynitride, aluminum oxide, diamond like carbon (DLC), carbonnitride (CN), or other insulating materials by a thin film formingmethod such as plasma CVD and sputtering. Instead, the same material asthat of the channel protective film may be used, or a stack of thesematerials may also be used. Alternatively, the passivation film may beformed by discharging a composition containing insulating materialparticles by a droplet discharge method.

Subsequently, a liquid repellent material is formed over the source anddrain electrodes of the TFT by a droplet discharge method, spin coating,slit coating, spray coating or the like. Then, a mask formed of PVA,polyimide or the like is formed in an area in which a contact hole is tobe formed. The liquid repellent material may be formed of afluorine-based silane coupling agent such as FAS (fluoroalkyl silane).The mask may be formed by selectively discharging PVA, polyimide or thelike by a droplet discharge method.

The liquid repellent material is removed using the mask of PVA or thelike (FIG. 11B). The liquid repellent material may be removed by O₂ashing or atmospheric pressure plasma. The mask is removed thereafter bywater washing in the case of PVA, or by the N300 stripper or the like inthe case of polyimide.

A planarizing film 1551 is formed by a droplet discharge method, spincoating, slit coating or the like while leaving the liquid repellentmaterial in an area in which a contact hole is to be formed (FIG. 15B).At this time, the planarizing film 1551 is not formed over the area inwhich a contact hole is to be formed since a liquid repellent material1562 is applied thereon. In addition, the contact hole is not invertedtapered. It is preferable that the planarizing film 1551 is selectivelyformed by a droplet discharge method using an organic resin such asacryl, polyimide and polyamide, or an insulating film containing asiloxane-based material and including a Si—O bond and a Si—CH_(x) bond.After forming the planarizing film 1551, the liquid repellent material1562 is removed by O₂ ashing or atmospheric pressure plasma. In the casewhere a passivation film is provided, it is removed as well.

A pixel electrode 1526 connected to the source electrode or the drainelectrode through the contact hole is formed over the planarizing film1551 by a droplet discharge method. The material of the pixel electrode1526 is selected from a transparent conductive material such as ITO andITSO or a reflective conductive material such as MgAg depending onwhether the pixel electrode 1526 transmits light or not.

Then, a liquid crystal layer 1571 is disposed between a TFT substrateand a counter substrate 1574, and sealed with a sealing member 1576. Acolumnar spacer 1575 is formed over the TFT substrate in accordance witha depression of the contact portion on the pixel electrode 1526. Theheight of the columnar spacer 1575 is 3 to 10 μm, though it depends on aliquid crystal material to be used. The depression is formed in thecontact portion depending on the contact hole. Thus, by forming thecolumnar spacer 1575 in the depression, misalignment of liquid crystalmolecules can be prevented.

An alignment film 1570 is formed over the TFT substrate, and thenrubbing treatment is performed. A transparent conductive film 1573 andan alignment film 1572 are formed over the counter substrate 1574.Subsequently, the TFT substrate and the counter substrate 1574 areattached to each other with the sealing member 1576, and a liquidcrystal is injected therein to form the liquid crystal layer 1571. Insuch a manner, an active matrix liquid crystal display device can becompleted.

The liquid crystal layer 1571 can be formed by dip coating (pumping upmethod) in which after both of the substrates are attached to each otherwith the sealing member, one side provided with a liquid crystalinjection opening of the attached substrate (cell) is soaked in liquidcrystals to inject the liquid crystal into the inside of the cell bycapillary phenomenon. Alternatively, the liquid crystal layer 1571 canbe formed by so-called liquid crystal discharging as shown in FIG. 16,in which liquid crystals are discharged from a nozzle (dispenser) 326over a substrate 321 provided with a sealing member 328 and a barrierlayer 329, and then a counter substrate 330 is attached to the substrate321. In particular, the liquid crystal discharging is effective in thecase of a large substrate being used. The barrier layer 329 shown inFIG. 16 is provided for preventing chemical reaction between a liquidcrystal molecule 327 and the sealing member 328. In the case where bothof the substrates are attached to each other, an alignment marker 322 or331 is detected by an imaging means 323, and a stage 320 provided withboth of the substrates is controlled through a CPU 324 and a controller325.

Subsequently, a FPC (Flexible Printed Circuit) 1544 is attached to theterminal electrode 1542 with an anisotropic conductive film 1543 by aknown method. The terminal electrode 1542 is desirably formed of atransparent conductive film and connected to the wiring 1540 that isformed simultaneously with the gate electrode.

Through the aforementioned steps, an active matrix LCD substrateincluding a pixel portion 654, a driver circuit portion 653 and aterminal portion 652 is completed (FIG. 15C). Note that referencenumeral 1500, 1510, 1511 to 1514 denote a substrate, an insulating film,source and drain electrodes respectively. Further, reference numeral1516 and 1518 denote island shape semiconductor films. The structure ofa TFT used in the LCD substrate is not limited to the one shown in thisembodiment. Note that this embodiment can be implemented in combinationwith other embodiment modes and embodiments.

Embodiment 4

A liquid crystal TV set can be completed using a liquid crystal displaypanel manufactured according to Embodiment 3. FIG. 17 is a block diagramshowing the main configuration of a liquid crystal TV set. The inventioncan be applied to any kind of a liquid-crystal display panel 1701: adisplay panel in which only a pixel portion is formed over the displaypanel, and a scan line driver circuit 1703 and a signal line drivercircuit 1702 are mounted thereto by TAB; a display panel in which apixel portion as well as the scan line driver circuit 1703 and thesignal line driver circuit 1702 at the periphery thereof are mountedover the display panel by COG; and a display panel in which a pixelportion and the scan line driver circuit 1703 are integrally formed overa substrate by using TFTs formed of SAS, and the signal line drivercircuit 1702 is mounted thereto as a driver IC.

Other external circuits include, at a video signal input side, a videosignal amplifier circuit 1705 for amplifying a video signal received bya tuner 1704, a video signal processing circuit 1706 for converting theamplified signal into a color signal corresponding to each color of red,green and blue, a control circuit 1707 for converting the video signalso as to be inputted to a driver IC, and the like. The control circuit1707 outputs a signal to each of the scan line side and the signal lineside. In the case where the liquid crystal display panel is driven in adigital manner, a configuration in which an input digital signal isdivided into m signals to be supplied may be adopted by providing asignal divider circuit 1708 in the signal line side.

An audio signal received by the tuner 1704 is transmitted to an audiosignal amplifier circuit 1709, an output of which is supplied to aspeaker 1713 through an audio signal processing circuit 1710. A controlcircuit 1711 receives receiving station (received frequency) data andvolume control data from an input portion 1712, and transmits thesignals to the tuner 1704 or the audio signal processing circuit 1710.

By incorporating such a liquid crystal module into a housing, a TV setas shown in FIG. 25A can be completed. It is needless to say that theinvention can be applied to various apparatuses other than the TV set,such as a monitor of a personal computer, and in particular a largedisplay medium such as an information display panel in the station orthe airport, and an advertisement board on the street.

Embodiment 5

In this embodiment, modularization of the EL display panel or LCD panelof the aforementioned embodiment is described with reference to FIGS.18A and 18B.

In a module shown in FIG. 18A, driver ICs including driver circuits areformed at the periphery of a pixel portion 701 by COG (Chip On Glass).It is needless to say that the driver ICs may be mounted by TAB (TapeAutomated Boding).

A substrate 700 is attached to a counter substrate 703 with a sealingmember 702. The pixel portion 701 may utilize a liquid crystal as adisplay medium as shown in Embodiments 3 and 4, or may utilize an ELelement as a display medium as shown in Embodiments 1 and 2. Anintegrated circuit formed of a single crystalline semiconductor or apolycrystalline semiconductor may be used as driver ICs 705 a and 705 band driver ICs 707 a, 707 b and 707 c. The driver ICs 705 a and 705 band driver ICs 707 a, 707 b and 707 c are supplied with a signal or apower source through FPCs 706 a and 706 b and FPCs 704 a, 704 b and 704c, respectively.

In a module shown in FIG. 18B, a gate driver 712 is integrally formedover the substrate 700 and connected to an FPC 710. The gate driver 712is desirably formed of a semi-amorphous silicon (SAS) with highmobility. A source driver 709 is formed separately using polycrystallinesilicon, attached to the substrate 700 after being cut into a stickshape, and connected to an FPC 711. The gate driver 712 may also beformed separately using polycrystalline silicon and attached after beingcut into a stick shape. When the driver portion (driver circuit portion)is formed over the substrate integrally or attached after being cut intoa stick shape, manufacturing steps can be simplified as compared with inthe case of attaching a number of IC chips, and the substrate area canbe used efficiently.

This embodiment can be implemented in combination with other embodimentmodes and embodiments.

Embodiment 6

Described in this embodiment is the case in which a scan line drivercircuit is formed over a substrate 100 by using a semiconductor layerformed of SAS.

FIG. 19 is a block diagram showing a scan line driver circuit structuredby N-channel TFT using SAS with a field effect mobility of 1 to 15 cm2/V·sec.

In FIG. 19, a block denoted by 500 corresponds to a pulse output circuitfor outputting one stage of sampling pulses, and a shift register isconstituted by n pulse output circuits. Reference numeral 501 denotes abuffer circuit to which a pixel 502 is connected.

FIG. 20 shows a specific configuration of the pulse output circuit 500,which includes N-channel TFTs 2001 to 2013. The size of each TFT may beset in view of the operating characteristics of an N-channel TFT usingSAS. For example, when the channel length is 8 μm, the channel width maybe set at 10 to 80 μm.

FIG. 21 shows a specific configuration of the buffer circuit 501, whichalso includes N-channel TFTs 2120 to 2135. The size of each TFT may beset in view of the operating characteristics of an N-channel TFT usingSAS. For example, when the channel length is 10 μm, the channel widthmay be set at 10 to 1800 μm.

This embodiment can be implemented in combination with other embodimentmodes and embodiments.

Embodiment 7

A liquid crystal display device according to the invention may be formedby a droplet discharge system as shown in FIG. 24. First, circuit designis performed using a circuit design tool 2400 such as CAD, CAM and CAE,thereby desired thin film and position of an alignment marker aredetermined.

Next, a thin film pattern data 2401 including the designed thin film andthe position of an alignment marker is inputted to a computer 2402 forcontrolling a droplet discharge apparatus through recording medium orinformation network such as LAN (Local Area Network). In accordance withthe thin film pattern data 2401, a nozzle having an optimum orifice thatstores a composition containing a material of the thin film or isconnected to a tank storing the composition is determined among nozzles(cylindrical device with a small orifice for ejecting liquid or gas) ofa droplet discharge means 2403, and then a scanning path (movement path)of the droplet discharge means 2403 is determined. In the case of anoptimum nozzle being determined in advance, the movement path of thenozzle only is required to be determined.

By photolithography or laser irradiation, an alignment marker 2417 isformed on a substrate 2404 on which the thin film is to be formed. Then,the substrate provided with the alignment marker 2417 is disposed on astage 2416 in the droplet discharge apparatus, the position of thealignment marker 2417 is detected by an imaging means 2405 of theapparatus, and the detected data is inputted to the computer 2402 aspositional information 2407 through an image processing apparatus 2406.The computer 2402 compares the thin film pattern data 2401 designed byCAD or the like with the positional information 2407 of the alignmentmarker 2417 detected by the imaging means 2405, and aligns the substrate2404 and the droplet discharge means 2403.

Subsequently, a composition 2418 is discharged by the droplet dischargemeans 2403 controlled by a controller 2408 in accordance with thedetermined scanning path, thereby a desired thin film pattern 2409 isformed. The discharge amount of the composition can be arbitrarilycontrolled by selecting the diameter of the orifice. However, thedischarge amount changes slightly with other conditions such as themovement speed of the orifice, the distance between the orifice and thesubstrate, the discharge speed of the composition, atmosphere in adischarge space, and temperature and humidity in the space. Therefore,these conditions can also be desirably controlled. It is desirable thatthese conditions be compiled into a database 2419 for each material ofthe composition by obtaining optimum conditions through experiments andevaluations in advance.

The thin film pattern data 2401 includes, for example, a circuit diagramor the like of an active matrix TFT substrate used in a liquid crystaldisplay device, an EL display device or the like. A circuit diagram in acircle of FIG. 24 schematically shows a conductive film used for such anactive matrix TFT substrate. Reference numeral 2421 denotes a so-calledgate wiring, 2422 denotes a source signal line (2nd wiring), and 2423denotes a pixel electrode, a hole injection electrode or an electroninjection electrode. Reference numeral 2420 denotes a substrate and 2424denotes an alignment marker. Needless to say, the thin film pattern 2409corresponds to the gate wiring 2421 included in the thin film patterndata 2401.

The droplet discharge means 2403 has nozzles 2410, 2411 and 2412 thatare integrally formed, though the invention is not limited to such astructure. Each of the nozzles 2410, 2411 and 2412 includes a pluralityof orifices 2413, 2414 and 2415 respectively. The thin film pattern 2409is formed by selecting the predetermined orifice 2413 of the nozzle2410.

The droplet discharge means 2403 desirably includes a plurality ofnozzles having different diameter of orifice, discharge amount andnozzle pitch, so that a thin film pattern of any line width can beformed and tact time can be reduced. Further, it is desirable that thedistance between adjacent orifices is as small as possible. In addition,each nozzle desirably has a length of 1 m or more for discharging withhigh throughput on a large substrate having a side of 1 m or more. Thenozzle may be elasticated so as to control the distance between adjacentorifices. Moreover, it is desirable that a nozzle or a head is setobliquely in order to achieve high resolution, that is to draw a patternsmoothly. According to this, a large-area pattern such as a rectangularpattern can be drawn.

It is also possible to provide another head with a different nozzlepitch in parallel with one head. In that case, the diameter of eachorifice may be the same or different.

In the case where the droplet discharge apparatus has a plurality ofnozzles as described above, a standby chamber for storing a nozzle thatis not in use is required to be provided. When a gas supply means and ashower head are provided in the standby chamber, the nozzle can beplaced under the same atmosphere of a gas as the solvent in thecomposition, therefore, drying can be prevented to a certain degree.Further, it is possible to provide a clean unit or the like to supplypurified air and reduce dust in an operating area.

In the case where the distance between adjacent orifices cannot be madesmall due to the specification of the nozzle, a nozzle pitch maypreferably be designed to be integral times as large as the pixels of adisplay device. Accordingly, the composition can be discharged by movingthe nozzle.

As the imaging means 2405, a camera such as CCD (Charge Coupled Device)for converting the light intensity into an electrical signal may beused.

According to the aforementioned method, the thin film pattern 2409 canbe formed by fixing the stage 2416 on which is mounted the substrate2404 and scanning the droplet discharge means 2403 along a determinedpath. Alternatively, the thin film pattern 2409 may be formed by fixingthe droplet discharge means 2403 and transferring the stage 2416 in thedirection of x, y and θ along a determined path based on the thin filmpattern data 2401. At this time, in the case where the droplet dischargemeans 2403 has a plurality of nozzles, a nozzle having an optimumorifice that stores a composition containing a material of the thin filmor is connected to a tank storing the composition is required to bedetermined.

According to the aforementioned method, the thin film pattern 2409 isformed by discharging droplet using only one predetermined orifice ofthe nozzle 2410. However, the composition may be discharged from aplurality of orifices in accordance with the line width or filmthickness of a thin film to be formed.

Alternatively, a redundant function may be provided by using a pluralityof nozzles. For example, when the discharge conditions are controlled sothat a composition is discharged from the nozzle 2412 (or 2411) firstand the identical composition is discharged from the nozzle 2410, thecomposition can be discharged from the nozzle 2410 even when the formernozzle 2412 has a problem such as clogging of the orifice. Therefore, atleast broken wirings and the like can be prevented.

Alternatively, when the discharge conditions are controlled so that acomposition is discharged from a plurality of nozzles each having anorifice with a different diameter, a planar thin film can be formed in areduced tact time. This method is particularly suitable for theformation of a thin film such as a pixel electrode of an LCD, whichrequires planarity and has a large area to be discharged with acomposition.

Further, when the discharge conditions are controlled so as to dischargea composition from a plurality of nozzles each having an orifice with adifferent diameter, a wiring pattern with different line widths can beformed at a time.

Further, when the discharge conditions are controlled so that acomposition is discharged from a plurality of nozzles each having anorifice with a different diameter, the composition can be filled in anopening with high aspect ratio, which is provided in a part of aninsulating film. According to such a method, voids (worm holes producedbetween the insulating film and a wiring) can be prevented, whichenables the formation of a planarized wiring.

According to the aforementioned droplet discharge means that includes aninput means for inputting thin film pattern data, a setting means forsetting a movement path of a nozzle for discharging a compositioncontaining a material of the thin film based on the data, an imagingmeans for detecting an alignment marker formed on a substrate, and acontrol means for controlling the movement path of the nozzle, themovement path of the nozzle or the substrate in droplet discharging canbe controlled accurately. When a computer for controlling the dropletdischarge means reads a control program of the composition dischargeconditions, various conditions such as the movement speed of an orificeor a substrate, the discharge amount of a composition, the distancebetween the orifice and the substrate, the discharge speed of thecomposition, atmosphere, temperature and humidity in a discharge space,and a heating temperature of the substrate can be controlled accuratelyin accordance with a discharged composition or a pattern thereof.

Accordingly, a thin film or a wiring having a desired width, thicknessand shape can be formed accurately in a desired area in a reduced tacttime and with high throughput, which results in improved yield of anactive element such as a TFT formed by using the thin film or thewiring, and a liquid crystal display (LCD), a light emitting device suchas an organic EL display, an LSI and the like formed by using the activeelement. In particular, according to the invention, a thin film patternor a wiring pattern can be formed in an arbitrary area while controllingthe width, thickness and shape thereof. Thus, a large-area activeelement substrate and the like can be formed with high yield at lowcost.

Embodiment 8

As an example of an electronic apparatus using the module shown inEmbodiments 2, 4 and 5, a TV set, a portable book (electronic book) anda mobile phone can be completed as shown in FIGS. 25A to 25C.

A TV set shown in FIG. 25A includes a housing 2501 incorporating adisplay module 2502 using a liquid crystal or an EL element. Such a TVset enables TV broadcast reception through a receiving portion 2505 aswell as one-way (from sender to recipient) or two-way (between senderand recipient) communication through a modem 2504 that is linked to acommunication network by wired or wireless connections. The TV set canbe operated by a switch incorporated in the housing 2501 or a remotecontrol 2506 formed separately. The remote control 2506 may include adisplay portion 2507 for displaying information to be outputted.

The TV set may also include a main display screen 2503 as well as a subdisplay screen 2508 that is formed of a second display module anddisplays channel, volume and the like. In such a TV set, the maindisplay screen 2503 may be structured by an EL display module with wideviewing angle, while the sub display screen 2508 may be structured by aliquid crystal display module with low power consumption. Alternatively,in order to give priority to power consumption, the main display screen2503 may be structured by a liquid crystal display module, while the subdisplay screen 2508 may be structured by an EL display module so as tobe capable of flashing.

FIG. 25B is a portable book (electronic book) that includes a main body3101, display portions 3102 and 3103, a recording medium 3104, anoperating switch 3105, an antenna 3106 and the like.

FIG. 25C is a mobile phone that includes a display panel 3001 and anoperating panel 3002 that are connected to each other with a connectingportion 3003. The angle θ at the connecting portion 3003 between thedisplay panel 3001 including a display portion 3004 and the operatingpanel 3002 including operating keys 3006 can be changed arbitrarily. Themobile phone further includes an audio output portion 3005, a powersource switch 3007, an audio input portion 3008, and an antenna 3009.

In either case, according to the invention that allows the manufacturingsteps to be simplified, a TV set, a portable book and a mobile phoneeach having a large screen can be manufactured with high yield at lowcost.

Embodiment 9

Described in this embodiment is the size of a mask pattern in theformation of a contact hole described in FIGS. 1A to 1F, which dependson the concentration of solute.

First, a tray including a glass substrate and fluoroalkyl silane (FAS)is set on a hot plate heated at 170° C. The tray is sealed and heatedfor 10 minutes, thereby the FAS is absorbed on the surface of the glasssubstrate. Then, the surface of the glass substrate is washed withethanol. A composition for forming a mask pattern is selectivelydischarged by a droplet discharge method in an area on the FAS where acontact hole is to be formed. Subsequently, heat treatment is applied ata temperature high enough to evaporate a solvent. In this embodiment,heat treatment is performed at a temperature of 120° C. for 10 minutes.

Measured here is the size of a mask pattern formed on the FAS whenvarying the concentration of solute in a composition for forming a maskpattern. In this embodiment, a sample (a), a sample (b) or a sample (c)is used as the composition for forming a mask pattern. The sample (a) tothe sample (c) respectively correspond to (a) a solution (product ofToray Industries, Inc., DL1602) containing polyimide as a solute and νbutyrolactone as a solvent; (b) a solution containing polyvinyl acetate(PVAc) as a solute and ν butyrolactone as a solvent; and (c) a solutioncontaining polyvinyl acetate (PVAc) as a solute and ethylcellosolve:butyl cellosolve=1:1 as a solvent. In this embodiment, theconcentration of solute is varied by changing the amount of solventwhich a composition for forming a mask pattern is diluted, and the sizeis measured five times for each concentration. TABLE 1 shows the resultof the sample (a), TABLE 2 shows the result of the sample (b), and TABLE3 shows the result of the sample (c). TABLE 1 to TABLE 3 arecollectively shown in FIG. 26.

TABLE 1 size [μm] first second third fourth fifth time time time timetime concentration 12 40.2 40.2 40.2 39.9 40.5 of solute [wt %] 6 33.233.5 32.5 33.7 33.3 3 27.4 27.6 28 27 27.6 1.2 21.6 21.6 20.8 21 21.30.2 14 14.4 14.4 14.9 14.2

TABLE 2 size [μm] first second third fourth fifth time time time timetime concentration 5 26 26.2 25.9 26.6 26 of solute [wt %] 2.5 20.9 21.221.6 21.3 21.1 1 17.2 16.7 16.9 16.9 16.3

TABLE 3 size [μm] first second third fourth fifth time time time timetime concentration 5 31.6 31.3 31.2 31.2 31.9 of solute [wt %] 2.5 23.226.5 26 24.3 24.6 1 15.4 16.4 16.2 17.4 18.2

As shown in FIG. 26, when a composition for forming a mask pattern isdischarged on a substrate on which the FAS is formed, the size of themask pattern can be controlled by controlling the concentration ofsolute. With the decrease in the concentration of solute, the size ofthe mask pattern decreases. Accordingly, when a composition for forminga mask pattern is discharged on a substrate on which the FAS is formed,the contact hole size can be controlled by controlling the concentrationof solute. The decrease in the concentration of solute allows thecontact hole size to decrease.

According to the invention, an island shape organic film is selectivelyformed over a semiconductor layer, a conductive layer or an insulatinglayer, and an insulating film is formed around the island shape organicfilm. Therefore, a contact hole and the insulating film can be formedwithout conventional exposure and developing steps using a resist mask,which results in drastically simplified manufacturing steps. Further,according to the invention, a manufacturing method of a semiconductordevice with high throughput and yield can be provided at low cost.

The invention having such advantageous effects can be applied to amanufacturing method of various kinds of semiconductor devices such asan inverted staggered TFT and a top gate TFT as shown in theembodiments. In addition, the invention can be applied in various fieldssuch as an active matrix substrate using the semiconductor device, aliquid crystal display device using such a substrate, a display such asan EL display device, and a contact hole in an LSI.

This application is based on Japanese Patent Application serial No.2004-022039 filed in Japan Patent Office on Jan. 29, 2004, the contentsof which are hereby incorporated by reference.

1. A method of manufacturing a semiconductor device, comprising: formingan organic film over a substrate; forming a mask pattern over theorganic film; patterning the organic film to form an island shapeorganic film using the mask pattern as a mask; removing the maskpattern; forming an insulating film around the island shape organicfilm, wherein a contact hole is formed in the insulating film at aposition of the island shape organic film; removing the island shapeorganic film in the contact hole; and forming a conductor in the contacthole, after removing the island shape organic film.
 2. A method ofmanufacturing a semiconductor device, comprising: forming an organicfilm over a substrate by plasma treatment under an atmosphere containingfluorine; forming a mask pattern over the organic film; patterning theorganic film to form an island shape organic film using the mask patternas a mask; removing the mask pattern; forming an insulating film roundthe island shape organic film, wherein a contact hole is formed in theinsulating film at a position of the island shape organic film; removingthe island shape organic film in the contact hole; and forming aconductor in the contact hole, after removing the island shape organicfilm.
 3. The method of manufacturing a semiconductor device according toclaim 1, wherein the mask pattern is formed of PVA (polyvinyl alcohol)or polyimide.
 4. The method of manufacturing a semiconductor deviceaccording to claim 2, wherein the mask pattern is formed of PVA(polyvinyl alcohol) or polyimide.
 5. The method of manufacturing asemiconductor device according to claim 1, wherein the insulating filmis formed of a polyimide-based resin, an acryl-based resin, apolyamide-based resin, or a material that has a backbone structureobtained by binding silicon to oxygen, and contains at least onehydrogen substituent, or further has at least one substituent selectedfrom fluorine, an alkyl group, or aromatic hydrocarbon in addition tohydrogen.
 6. The method of manafacturing a semiconductor deviceaccording to claim 2, wherein the insulating film is fanned of apolyimide-based resin, an acryl-based resin, a polysinide-based resin,or a material that has a backbone structure obtained by binding siliconto oxygen, and contains at least one hydrogen substituent, or furtherhas at least one substituent selected from fluorine, an alkyl group, oraromatic hydrocarbon in addition to hydrogen.
 7. The method ofmanufacturing a semiconductor device according to claim 1, wherein theinsulating film is formed by slit coating or spin coating.
 8. The methodof manufacturing a semiconductor device according to claim 2, whereinthe insulating film is formed by slit coating or spin coating.
 9. Amethod of manufacturing a display device, comprising: forming an organicfilm over a thin film transistor; forming a mask pattern over theorganic film; patterning the organic film to form an island shapeorganic film using the mask pattern as a mask; removing the maskpattern; forming an insulating film around the island shape organicfilm, wherein a contact hole is formed in the insulating film at aposition of the island shape organic film; removing the island shapeorganic film in the contact hole; and forming a conductor in the contacthole, after removing the island shape organic film.
 10. A method ofmanufacturing a display device, comprising: forming an organic film overa thin film transistor by plasma treatment under an atmospherecontaining fluorine; forming a mask pattern over the organic film;patterning the organic film to form an island shape organic film usingthe mask pattern as a mask; removing the mask pattern; forming aninsulating film around the island shape organic film, wherein a contacthole is formed in the insulating film at a position of the island shapeorganic film; removing the island shape organic film in the contacthole; and forming a conductor in the contact hole, after removing theisland shape organic film.
 11. The method of manufacturing a displaydevice according to claim 9, wherein the display device is an EL displaydevice comprising a layer containing an organic compound or an inorganiccompound over the conductor.
 12. The method of manufacturing a displaydevice according to claim 10, wherein the display device is an ELdisplay device comprising a layer containing an organic compound or aninorganic compound over the conductor.
 13. The method of manufacturing adisplay device according to claim 9, wherein the display device is aliquid crystal display device comprising a liquid crystal layer over theconductor.
 14. The method of manufacturing a display device according toclaim 10, wherein the display device is a liquid crystal display devicecomprising a liquid crystal layer over the conductor.
 15. The method ofmanufacturing a display device according to claim 9, wherein the maskpattern is formed of PVA (polyvinyl alcohol) or polyimide.
 16. Themethod of manufacturing a display device according to claim 10, whereinthe mask pattern is formed of PVA (polyvinyl alcohol) or polyimide. 17.The method of manufacturing a display device according to claim 9,wherein the insulating film is formed of a polyimide-based resin, anacryl-based resin, a polyamide-based resin, or a material that has abackbone structure obtained by binding silicon to oxygen, and containsat least one hydrogen substituent, or further has at least onesubstituent selected from fluorine, an alkyl group, or aromatichydrocarbon in addition to hydrogen.
 18. The method of manufacturing adisplay device according to claim 10, wherein the insulating film isformed of a polyimide-based resin, an acryl-based resin, apolyamide-based resin, or a material that has a backbone structureobtained by binding silicon to oxygen, and contains at least onehydrogen substituent, or further has at least one substituent selectedfrom fluorine, an alkyl group, or aromatic hydrocarbon in addition tohydrogen.
 19. The method of manufacturing a display device according toclaim 9, wherein the insulating film is formed by slit coating or spincoating.
 20. The method of manufacturing a display device according toclaim 10, wherein the insulating film is formed by slit coating or spincoating.
 21. The method of manufacturing a display device according toclaim 9, wherein the display device is applied to an electronicapparatus selected from the group consisting of a TV set, a portablebook and a mobile phone.
 22. The method of manufacturing a displaydevice according to claim 10, wherein the display device is applied toan electronic apparatus selected from the group consisting of a TV set,a portable book and a mobile phone.